WE all know size does matter, but how about speed? The only serious criticism you could make about the diesel-engined 2.0 D-4D Toyota Avensis is that its acceleration feels sluggish.

Normally, we leave the 0-62mph 'dash' figures to the consumer motoring magazines. But the Avensis raises an issue because it lacks the pep of the Ford Mondeo 2.0 TDCi. There are two important points, though. The performance comparison isn't the end of the world and other factors make the Avensis appealing to the 'thinking' business driver.

The D-4D's top speed of 121mph is only 9mph slower than the Avensis 2.0 VVT-i with double overhead camshaft, 16-valve petrol engine, so both can easily speed you into trouble.

The sprightly Mondeo diesel pretty well matches the petrol Avensis and is more than a second faster to 0-62mph than the Toyota diesel (11.4 seconds, compared to 9.8 seconds for the Ford). But keep up the revs in the Avensis when accelerating through the gears and you will not be embarrassed.

Government determination to reduce average speeds on Britain's congested roads mean that figures other than maximum speed and 0-62mph will become increasingly important.

Penalties for excessive speed – and rewards for exhaust cleanliness – will increase.

This is why the Avensis D-4D is a truly modern car. It was the first, from launch, to use a range of petrol and diesel engines that all conform to Euro IV emissions legislation. Later this year, Toyota will introduce a D-CAT (diesel clean advanced technologies) engine that it says achieves a new standard in emissions for diesels.

The D-4D's clean-living engine means it falls into the lowest (15%) benefit-in-kind tax band, and escapes the usual 3% penalty so far levied on diesels. It's important for fleet drivers to study the statistics, but comfort and reliability, that the Avensis has in spades, is even more essential.

Company car tax bill 2003/04 (22% tax-payer): £43 per month