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The turbo touch transforms a diesel

CAN a diesel-engined car seriously qualify for the executive class? Diesels are rattly at start-up and tickover. They are fairly lethargic under acceleration. If you are careless at a filling station the pong of diesel fuel can stay on your person or clothing for hours.

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And diesel fuel is a ludicrous price in this country. However, the answer to the original question is yes, especially if you think either of a large-capacity unblown diesel engine or a turbocharged design. The turbo releases the performance unable to get out of most unblown diesels. Mercedes makes what are regarded by many people as the top unblown diesels, engines which can easily last towards the 200,000-mile mark. Peugeot and Citroen share well-regarded diesel designs in the under two-litre class, while Renault has the advantage of 2.2-litre power, one size up. The French are keen on turbo diesels, thanks partly to their government's more enlightened attitude to diesel fuel taxation. The Citroen XM in turbo diesel form is a splendid long-legged autoroute car, and so are the Renault Safrane and Peugeot 605. Germany has recently produced two excellent and advanced turbo diesels. BMW fits a 2.5-litre unit to its own cars, as well as supplying it to Vauxhall for the Omega, and Land Rover for individual models in the Discovery and Range Rover catalogues. Audi's 150bhp TDI combines strong performance with notably good economy. Volvo takes some of its turbo diesel engines from that source, and has a particularly strong turbo diesel 850 saloon and estate. Volkswagen offers its biggest model, the Passat, with a turbo diesel engine bearing the Umwelt (or environment) name. At the top end of the Carina range, Toyota makes great play with the fuel economy of its lean-burn petrol engines, but there is a turbo diesel Carina too. Of the other Japanese manufacturers, Honda rather grudgingly fits the two-litre Rover turbo diesel to the Accord because of British and European enthusiasms it hardly shares, and Nissan slips in a diesel Primera, but the rest leave diesels to 4x4s and MPVs, or ignore them altogether. Rover's well-designed two-litre turbo diesel, especially in the 600 and 800, is marketed in the heart of executive car territory. Ford threads turbo diesel options through the Mondeo and Scorpio ranges. One curiosity about turbo diesel engines is that they go well with some manufacturers' automatic transmissions. The almost inevitable slight turbo lag seems to mask any delayed kick-down response from the automatic box, and vice versa. You can expect pretty good cruising speed fuel returns from a turbo diesel, but anybody who regularly uses the massive mid-range torque to get maximum acceleration should be prepared to see the fuel bills climb. RF

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