BEING an avid reader of Fleet NewsNet it can't have escaped your attention that major changes are being introduced in April regarding company car taxation.

And you will also know that we have been beating the diesel drum for a long time as the way to help your drivers cut their tax bills.

So far diesel engines have been limited to rather sober saloons, estates and hatchbacks. But Peugeot, for a long time the leader of the oil burning pack with its HDi range of common rail units, is offering another diesel dimension with the launch of a diesel-engined version of its svelte Pininfarina designed 406 Coupe.

The idea may seem strange - after all diesel engines are not as glamorous as their petrol drinking counterparts - but the idea has some logic behind it. With their increased torque offering, diesel cars have much more performance available for real-world driving than similar-sized petrol units and the fuel economy savings are obvious.

But can a diesel coupe tempt buyers away from their V6 models? Only time will tell, and so far only three manufacturers have taken the coupe diesel plunge: Peugeot with the 406, Saab with the 9-3 TiD and Mercedes-Benz with the CDI Sports Coupe.

For the purposes of this test we have omitted the Saab 9-3 because at £17,970 on-the-road it would be an unfair comparison with the 406 and Mercedes-Benz. Instead we have chosen the two other petrol 406 Coupes in 2.0-litre SE and 3.0-litre V6 guises and a top-spec Mercedes-Benz Sports Coupe in C220 CDI Evo spec with the Panorama glass roof.

At £24,995 on-the-road the 406 Coupe HDi SE costs £1,000 less than its V6 brother but £2,300 more than the 2.0-litre petrol SE. At £24,510 on-the-road, the Mercedes-Benz is, surprisingly, cheaper than the 406 HDi. And with a CAP Monitor residual value forecast over three years/ 60,000 miles of 42%, the Mercedes-Benz will 'lose' £14,210.

The 406 HDi Coupe, which is predicted to retain 32% of its value over the same cycle, will 'lose' £16,995 while the 406 2.0 SE will lose £15,470 and the 406 V6 £18,645. So with a cheaper front-end price and much better residual value forecast, the Mercedes-Benz is already making a strong case for itself.

On fuel economy, the Mercedes-Benz records a combined figure of 45.6mpg, slightly edging ahead of the 406 HDi on 44.1mpg. However, both are miles ahead of the petrol contenders here, with the 2.0 SE recording 34.0mpg and the V6 28.2mpg. (Although it may be unfair to compare diesel and petrol, it is worthwhile to show off the benefits of the HDi model over its petrol stablemates.)