Many people regard MPVs as big and bulky, and obviously have the suspicion that they are likely to be very heavy on fuel. Some can be, but this is a type of vehicle which in many cases has just the right aerodynamic approach to promote good fuel economy, and is very well suited to the turbo diesel engine.

An observed run, in bad weather last December, saw the four-strong Taylor family, complete with their overnight luggage, leave the VM Motori diesel engine factory near Bologna in a seven-seat Chrysler Voyager powered by the standard 2.5-litre VM turbo diesel. They headed through the Alpine passes in wind and heavy rain, and averaged 45mph on the 870-mile journey to Calais. Consumption worked out at a carefully measured 53mpg.

MPVs with a bonnet line which continues at the same angle onto the windscreen have a design approved by aerodynamicists, because it provides clean airflow over the vehicle. It is partly as a result of this that MPVs are often more economical, and more stable, than people not used to them appreciate.

Three designs - the Volkswagen Sharan, Ford Galaxy and Seat Alhambra - have the benefit of VW's well thought-of 110bhp intercooled turbo diesel engine.

More sporting performance may be available from some of the top-level petrol units such as the 1.8-litre light pressure turbo and the 2.8-litre VR6, but for a combination of a strong pull and good steady-speed economy the 110bhp TDI unit is hard to beat.

A peak torque figure of 173lb ft down at 1900rpm takes care of mid-range acceleration and flexibility. Out on the open road, a manual transmission version should manage about 54mpg according to the official ''extra urban'' test. And a figure of something like 44mpg overall, including town traffic work, ought to be easily achieved.

Even the less powerful 90bhp TDI unit, which obviously has a slightly harder job pulling the same weight, is not too stressed. A trip reported here last year, on a rather eccentric route from Dover to Munich to Gothenburg and back to Dover, saw a 90bhp Alhambra return just under 45mpg, and that was with a fair amount of 80-85mph cruising on the autoroutes and autobahns.