Government policy is torn between hating diesel cars, because their better economy means that they produce less revenue from fuel taxation, and pretending to love them because they produce less of the CO2 which is blamed for global warming. So extra taxes are applied to diesel cars - £10 extra on annual vehicle tax for all the lower pollution bands, and £5 extra (£165 instead of £160) for those emitting more than 185 g/km in exhaust gases. There is also an additional 3 per cent to be added to the car benefit charge for those provided with a free company car, which is assessed as a percentage of what the car cost when new.

  Even with these additions, diesel motoring is substantially cheaper because the typical diesel car consumes about a third less fuel than the equivalent petrol model. If we look at the Skoda Octavia 2.0 TDI tested in the group which follows, the official fuel consumption figure for the diesel with manual transmission is given as 47.9 mpg, though on our test it did even better, returning 54.1 mpg. By comparison, the 1.6-litre petrol version is credited with only 38.2 mpg.

  Such improvement in favour of diesel is not always the case, however, and the gain of the Renault Laguna 2.2 diesel over the equivalent 2-litre petrol model is only in the order of 10 per cent, so one needs to study the official figures carefully before joining the headlong rush to diesel.

   Additional benefits of diesel motoring are the much greater range between refuelling points, which is important as more and more roadside garages go out of business, and the quiet, relaxed cruising which results from high gearing to meet the diesel's reduced ability to rev fast.

  Enormous improvements have been made to diesels in recent years, so that they are now much quieter, accelerate faster, and give out less pollution. The result is that diesel car sales now outnumber petrol in many European countries such as Belgium, France, Austria and Spain, while in the UK they are catching up rapidly and now account for a third of all sales.

  In this review we have assessed six contenders for the executive market at various levels and prices. Except where stated otherwise, the fuel consumption figure given is that actually measured on our test, excluding towing where the car has also been tested as a tow-car. Acceleration from rest to 80 mph is given as a more representative figure than the much-quoted time to only 60 mph. Prices are subject to change, and may in any case be eligible for discounts, so please check with your dealer.

      
     

Skoda Octavia 2.0 TDI Elegance
For a long time the mainstay of the Volkswagen Group's diesel cars was a very efficient 1.9-litre four-cylinder engine, noted for quietness, smoothness and good economy. When a 2.0-litre diesel started to appear in many of the models, I wondered if the new power unit would be as good, or would economy be sacrificed in the interests of power, and was delighted to find it is even better. In this quite large and roomy car - the new Skoda Octavia is 4,572 mm (15ft) long, with hatchback body and a huge boot - a remarkable 54.1 mpg was returned overall. This is 6 mpg better than the official claimed figure.

  The engine is even quieter than the former 1.9-litre, especially at tickover which is when many diesels are obtrusive. It pulls smoothly and gives vigorous punch for third gear overtaking. A six-speed gearbox is standard with this engine, giving effortless fast cruising.

  Easy and reassuring to drive, the new Octavia has positive and pleasantly light steering, with very manageable and predictable handling, while the brakes are discs at all wheels, and give good response to light pedal loads. The steering wheel has a rather thin rim, but is neatly trimmed in stitched leather and a large central horn pad is in the centre boss. Beneath the wheel are lever switches for the indicators and cruise control on the left, and wipers with variable intermittent control on the right.

  Big-dial instruments are fitted, with commendably clear marking, and there's an easily understandable digital display for all audio and CD functions. An informative trip computer between the main instruments gives such information as fuel consumption, running time and average speed.

  A ratchet lever to the right of the driving seat gives height adjustment, and there's a large rotary knob for finely adjustable backrest angle as well as a smaller control for squab tension. So a really comfortable driving position can be set, and the front passenger also has these provisions. Below the front of the passenger seat a storage compartment drops down, marked as having a 1.5 kg weight limit - a good place to hide valuables from view. A drop-down container for glasses is just to the rear of the interior mirror. Many other stowage spaces are provided, including a deep compartment below the centre armrest. The rear seat is divided 40/60 to fold down readily on to the fixed one-piece cushion, yet there's also a ski flap through the centre of the backrest behind the folding armrest. Seats are firm but comfortable and upholstered in stitched leather. The luggage space is really generous, extending so far forward that you almost have to climb in to push something right to the end.

  An electrically operated sunroof is one of the few options on the new Octavia, but in other respects the top Elegance model as tested is well equipped, and packaged to please the buyer rather than to save cost wherever possible. Thus, it has a full-size alloy spare wheel in a well under the boot floor, and two good map lights. Combined red warning and puddle illumination lights come on in the bottom of the doors when any of the four doors is opened. A reverse warning system is standard on the TDI Elegance. A mournful gong reminds front occupants to fasten seat belts.

  If you are happy to go without some of the luxuries and generous equipment of the Elegance model, the TDI Classic is available with the same engine and six-speed gearbox at £15,300. Automatic transmission is available at just over £1,000 extra on both models. Whichever version is chosen, the whole of the new Octavia range seems to represent very good value.

Skoda Octavia TDI Elegance Hatchback 2.0 £16,400
Engine - 1,968 cc turbo direct injection
0-80 mph - 18.2 seconds
Maximum speed - 129 mph
Warranty - 3 years, unlimited mileage
                   - 10 years anti-corrosion
Fuel consumption - 54.1 mpg
CO2 emissions - 159 g/km (tax band B, £135)
Insurance - Group 9E

Citroën C5 HDi VTR
In September 2004, Citroën launched a surprise new package at the Paris Show to bring the big C5 range up to date, with improved styling, additional equipment, and a number of novel features. It has not yet been possible to carry out a full test, so the fuel consumption given in the data panel is Citroën's official figure for the model, but on the basis of a comparatively brief drive it was possible to conclude straight away that the new C5 is a very refined, comfortable and pleasing car, with the whole range offered here from October at prices which are highly competitive.

  Of the three diesel engines offered - 1.6, 2.0 and 2.2 - it was the middle one that was chosen, and it was very impressive to find how well this big car performs. It gives vigorous acceleration and leisurely cruising with its standard six-speed gearbox. In sixth, 100 mph would take little more than 3,000 rpm. This is likely to be the most popular version of C5, though there is also attraction in the 1.6 diesel, although it comes with only a five-speed gearbox. The 2.2 has four-speed automatic as standard.

  Citroën has refined its Hydro-pneumatic suspension over the years, and the latest version called Hydractive 3 gives an excellent blend of comfort with tautness for good roadholding. On some versions, a sport mode can be selected to make the ride and handling a little crisper, and there is automatic compensation for poor surfaces, giving a little more ground clearance, while at speed the ride height is lowered to reduce drag, giving better fuel economy, as well as aiding stability.

  With its much more attractive appearance, the C5 deserves a better name than the 'New Look' designation it has been given, though the slight penalty of the more flowing appearance is that it is 12 cm longer. The 2.0-litre diesel comes with VTR trim, or as the Exclusive. Body style is a roomy five-door hatchback, or for £1,100 more an Estate car body is available.

  Special features of the C5 are a 'wake-up' system to alert a driver who appears to be nodding off and allowing the car to cross the lane lines without first signalling an intention, and headlamps which turn up to 15 deg in response to the steering to light up the dead area when cornering. There's also a device to prevent the car from exceeding any chosen speed, which might appeal to those clinging on to nine licence points and waiting for the next camera flash to put them on the bus!

  Other features available or standard on certain models are rain sensing automatic wipers, front and rear parking warning systems, automatic switch-on headlamps, and a low tyre pressure warning system. Those looking for a big and comfortable diesel will be rewarded by a careful study of the equipment packaging and options list, and the C5 New Look looks set to please.

Citroën C5 HDi VTR Hatchback 2.0 £17,795
Engine - 1,997 cc turbo direct injection
0-80 mph - 18.7 seconds
Maximum speed - 127 mph
Warranty - 3 years, 60,000 miles
               - 12 years anti-corrosion
Fuel consumption (official figure, combined) - 35.3 mpg
CO2 emissions - 158 g/km (tax band B, £135)
Insurance - Group 10E

Vauxhall Vectra Estate car CDTI SRi 1.9
Several MPVs have electrically-operated sliding side doors, and many cars and estate cars have remote unlocking for the boot or tailgate, but the new Vauxhall Vectra Estate goes one further: it has the option of an electrically operated self-opening tailgate. It's certainly very convenient to go to the back of the Vectra Estate, just press a button, and see the tailgate open while you wait with armfuls of shopping.

  Unfortunately, it's not quite as easy as that, because safety legislation intrudes with all sorts of safeguards so that no one could ever be hurt by it and, of course, sue the company. So the button under the number plate plinth operates the tailgate only under the right conditions, which seemed to mean that the car has just been unlocked. Another problem is that if there is any luggage in the way, the tailgate can't complete its down cycle and goes into a part-closed condition in which it won't respond to any of the buttons.

  The opening or closing action is also rather slow, and a warning beeper sounds when the tailgate is beginning to open or close. This option costs £500.

  Perhaps more impressive than this gimmick was to find how well the new diesel engine with capacity of only 1.9-litre copes with this big car, giving spirited acceleration once it is revving well. At the lower speeds it is not too happy, and a subdued throbbing reminds the driver that this is only a four-cylinder with high gearing, and it would be helpful to change down. The engine is very quiet, and except at low engine speeds it pulls smoothly and vigorously. It's a 16-valve unit, and develops an impressive 150 bhp power output, with exhaust so clean that it meets the tough Euro 4 emission control regulations, bringing a useful reduction in annual tax. A less powerful variant of this engine is available at £500 less, but I recommend the 16-valve unit.

  A six-speed gearbox is fitted, and the change is easy to operate using an attractively styled gear shift with stitched leather around the front and a silvery top running down the back. The steering is accurate, with very good directional stability, but the suspension is not the best feature of the car, giving a rather bumpy ride with a lot of sharp reaction to small blemishes in the surface. The brakes bring good response to light pedal loads, but there is surprisingly long pedal travel.

  Caravanners will like the new type of built-in hideaway tow-hitch, which comes out from underneath on pulling a lever in the side of the load space. It stows away equally easily. This is a £600 option, and incorporates the electrical socket for connecting the caravan electrics, though this is of the Continental 13-pin type for which most British caravans will need an adaptor. Fuel consumption was 35.8 mpg when running solo, dropping to 25.8 when towing a 4.8-metre caravan.

  Well-shaped for comfort, the seats are upholstered in leather on the SRi, with electric adjustment for both. The driving seat has three memory buttons to set adjustments for different drivers. The rear seat, divided 60/40, folds down on to the fixed one-pieced cushion.

  A very attractive interior design provides an impressive console with an information display at the top showing time, outside temperature, and selected items from the computer read-out. It is also the navigation screen when this option has been specified.

   There are some surprising omissions from the standard equipment for the SRi in view of its price of £20,590. Thus, there are no map lights, no vanity mirror for the driver, and no sun roof. The passenger glove box is not lockable, and the windows are electric at the front only. But it does have a ski-flap through the wider section of the folding rear seat, map pockets on the seat backs, and a useful central compartment between the seats. Cruise control is fitted, and there is electric heating for the front seats. An effective audio unit has single slot loading as well as a four-disc magazine, and there is an efficient ventilation system.

  There is much to please the owner in the Vectra Estate, and for any of the items which one feels ought to be there, the options list is extensive to make good the deficiencies.

Vauxhall Vectra Estate car CDTI SRi 1.9 £20,590
Engine - 1,910 cc turbo direct injection
0-80 mph - 18.0 seconds
Maximum speed - 130 mph
Warranty - 3 years, 60,000 miles
              - 6 years anti-corrosion
Fuel consumption - 35.8 mpg
CO2 emissions - 165 g/km (tax band B, £135)
Insurance - Group 11E

MG ZT-T CDTi 135
In a busy week in which I covered over 900 miles with the ZT-T, I enjoyed it all the more as the miles mounted. There's nothing like experience of a car like the MG ZT-T to remind one that British cars still have a great deal to offer, can match or better their rivals on quality, and can often beat them on price. The MG ZT-T is the estate car version of MG's elegantly-styled model derived from the Rover 75, and with the more powerful of two diesel engines available, giving 131 bhp, it costs £21,595.

  When accelerating hard, which it does very well indeed, the engine gives a throaty growl, but when cruising it is exceptionally quiet for a diesel, swallowing the miles effortlessly and tirelessly. It serves as a very relaxing long journey car.

  There is no six-speed gearbox, which tends to be the norm for a car in this class, and in fifth the car speed at 1,000 rpm is relatively low at only 29.2 mph. But in spite of this, the fuel consumption is very reasonable, averaging 38.7 mpg overall, and 40 is obtainable with a little restraint.

  The disappointing aspect of the ZT-T is the suspension which gives a lot of recoil and plunge over undulations, with a sharp report over any bumps or blemishes such as cat's eye studs. The very low-profile tyres fitted accentuate the harshness of the ride, but the pay-off is very precise steering and a positive feel to the car on corners, with very good grip on wet roads. The steering wheel has audio switches on the left, cruise controls on the right, and there are two small but fairly easily found horn buttons. The steering column is adjustable in both directions.

  The seats wrap round comfortably and are upholstered in velour with stitched leather outer sections. Levers at the side enable driver and passenger to set the seat positions for optimum comfort without having to reach forward or under to get at the adjusters. Both front seats have height adjustment. The rear seat is divided 60/40 to fold down on to the one-piece cushion, and there is a ski-flap through the wider part. The practical interior layout includes a safety net to hold luggage at bay in the load space, and net pockets on the backs of the front seats.

  Because the clasp is not high enough above the seat, it is difficult to fasten the seat belt. Only the passenger has a vanity mirror, for which no light is provided.

  Remote central locking is provided, and the doors and tailgate lock automatically once 5 mph is exceeded. The driver then needs to operate the 'unlock' button near the handbrake, otherwise passengers can't get out - a feature which some women find irritating. A CD 6-pack unit takes up most of the space in the glove locker on the passenger side.

  I was particularly intrigued by some of the optional equipment on the test car, including the Highline navigation system which provides a clear map and sensible route instructions, and can be switched to give colour TV when the car is at rest. This option costs £2,325. Another expensive option for £1,195 includes rain sensing wipers, xenon headlamps, a trip computer and the Trafficmaster Alert system.

  With this option pack, Trafficmaster warnings of delays appear in simple abbreviated form between the speedometer and the rev counter. But the most attractive option of all, for a modest £210 extra, is the fuel-burning heater which can be set remotely to warm the interior before you get in - most welcome for a cold winter morning. This is exclusive to the diesel, and of course it is only for use with the car at rest and does not affect the standard heating and air conditioning systems. Being able to step into a warm car on the coldest morning would be a special bonus.

Please note this car is no longer available as a new purchase.

MG ZT-T Estate car 2.0 £21,595
Engine - 1,951 cc turbo direct injection
0-80 mph - 19.4 seconds
Maximum speed - 115 mph
Warranty - 3 years, 60,000 miles
               - 6 years anti-corrosion
Fuel consumption - 38.7 mpg
CO2 emissions - 163 g/km (tax band B, £135)
Insurance - Group 10

Renault Laguna Sport Tourer 2.2 dCi Privilège
Giving its Laguna estate car a more exciting title, Renault calls it the Sport Tourer, and a very sporting diesel estate it is, too. There's the usual Renault palette of engines from which to choose, including a 3-litre V6 petrol, but after trying the new 2.2-litre 16-valve diesel, this would be the obvious one for any thinking executive to select, bringing eager performance, effortless cruising, and good but not over-impressive fuel economy. There is also the advantage that automatic transmission is available, and with the advantage of Tiptronic control it makes the Laguna a very enjoyable car to drive. Simply move the selector lever across to the left to go into Tiptronic mode, and then a touch rearward gives a change down, or forward to change up. Changes are smooth and response excellent.

  As with most of the cars in this group, I was able to test the Laguna for caravan towing, and with this automatic it proved a first-rate tow-car, with a good reserve of power for overtaking.

  The Laguna is a big and very spacious estate car, so it's not unreasonable that fuel consumption was only 36.6 mpg when solo, dropping to 25.1 towing.

  Renaults are invariably well-equipped, and when looking at prices one needs to bear in mind that the Laguna comes as standard with such features as pull-up sun blinds for the rear side windows, a large tilt/slide sunroof, and a very impressive console on which are neatly laid out the audio and air conditioning controls with separate left and right adjustment for interior temperature. The radio is combined with a CD player and has repeater controls on a satellite within reach of the right hand on the steering wheel.

  The test car had the special equipment package called Privilège, which includes mixed velour and leather upholstery with leather trim on the door handles, a reverse warning system to advise when one is getting a little too close to any obstruction, and a tyre pressure monitoring system. An impressively good navigation system with clear colour mapping and providing sensible route directions is available as an extra at £1,500. Although it works so well, it is irritating that one has to press a button three times to pass through its security routine, agreeing, for example, that one will not drive over a cliff or the wrong way down a one-way street just because the navigation system tells one to do so! I found this a bit unnecessary, but one has to go through the rigmarole even after just stopping the engine momentarily.

  Renault's ignition 'key' is a card, about the size of a very small pocket calculator, and it is pushed into its slot, to put the engine on 'stand by'. Then, a touch on the 'Start' button triggers automatic start-up after a momentary delay to let the cold start glow plugs heat up. This takes only a second but might be slightly longer in winter, and one can be fastening the seat belt while start-up occurs automatically.

  Refreshing and relaxing to drive, with very comfortable seating and suspension, the Laguna 2.2 dCi takes little effort at the controls, and gives vigorous response with a lively feel on the road. Carrying capacity is generous, and the tailgate has a concealed electric release.

Renault Laguna Sport Tourer Privilège 2.2 dCi £21,815
Engine - 2,188 cc turbo direct injection
0-80 mph - 17.9 seconds
Maximum speed - 128 mph
Warranty - 3 years, 60,000 miles
                   - 12 years anti-corrosion
Fuel consumption - 36.6 mpg
CO2 emissions - 204 g/km (tax band D, £165)
Insurance - Group 10

Jaguar S-Type 2.7 D
For many years Jaguar has been losing out to competitors from Audi, Mercedes-Benz, BMW and others because it was not able to offer a diesel version, and as tax incentives and the appalling cost of fuel have tempted even executive company car users to contemplate diesels, something had to be done. Now that Jaguar is part of the Ford empire, the solution was a tie-up with PSA - the Peugeot-Citroën group - and the third phase of cooperative development produced a new 2.7-litre V6 diesel in June 2003. Earlier phases produced a smaller 2-litre diesel for the X-Type.

  Initially launched in the Jaguar S-Type, the V6 is expected later to become available in other models, and it's a twin-turbo unit giving an impressive 206 bhp. Even on start-up, which is when many diesels are noisy, the one in the Jaguar is notably quiet, and much of the time when cruising it is inaudible. There's a slight delay - no more than a second or two - before response is felt at low speed, then it gives vigorous punch as illustrated by the car's ability to accelerate through the gears to 80 mph in only 14.2 seconds.

  Installed longitudinally, the engine drives the rear wheels through manual or automatic transmissions, each having six speeds. The test car had the manual gearbox which has easy action, though the clutch is on the heavy side.

  All the lovely character of the Jaguar is present in this diesel version of the S-Type with very precise and extremely light steering, well-balanced handling, and responsive brakes which have internal venting for the discs at both front and rear wheels. A simple chromed switch controls the electrically-operated handbrake which is very convenient to use.

  Sumptuous seats are fitted with beige leather upholstery and electric adjustment with two memory settings to retain seat and mirror adjustments, and the steering wheel position is also electrically adjustable. When the engine is stopped and the key removed, the driving seat motors backward to its full extent to facilitate access in or out.

  The rear seat is divided in 60/40 format and the backrests fold down on to the fixed one-piece cushion. Release knobs for the backrests are located in the boot so that when the car is locked the seats cannot be folded down giving a thief access to the boot. Individual cupholders pop forward at the base of the rear seat, and at the front they are in recesses between the seats, covered by a slide-forward armrest.

  The S-Type test car was equipped for towing, and proved an excellent towcar giving reassuring stability while also having vigorous torque for acceleration and hill climbing. The effortless cruising pace with a caravan on tow makes a bit of a mockery of Britain's 60 mph trailer speed limit. The average fuel consumption when solo, 36.6 mpg, was still at a very reasonable 24.4 mpg when towing a 4.8-metre caravan.

  An excellent navigation system was fitted (costing £2,000 extra), with touch-screen control, but it's irritating that a destination cannot be set on the move, even if there is a passenger there to do it, and that every time the engine is re-started the driver must press the screen marking 'Agree' to an unnecessary legend about observing safety legislation. The screen is also positioned much too low.

  Further criticism of the interior goes to the instruments, which are ridiculously small, and to the computer read-outs in the bottom of the rev counter marked in black on green, which are very difficult to read. The boot extends well forward but is not very deep. The S-Type switches on its own lights, but the system is not sensitive enough, often leaving the car unlit in dull weather when dipped headlamps need to be turned on, which can of course be done manually. There is no automatic switch-on for the wipers, which many less expensive cars now offer.

  The S-Type is a most rewarding car to drive, with an excellent diesel engine, but it is spoilt by some annoying features.

Jaguar S-Type 2.7 D SE saloon £31,670
Engine - 2,720 cc twin-turbo direct injection
0-80 mph - 14.2 seconds
Maximum speed - 143 mph
Warranty - 3 years, unlimited mileage
                  - 6 years anti-corrosion
Fuel consumption - 36.6 mpg
CO2 emissions - 189 g/km (tax band D £165)
Insurance - Group 14