'DEALER research in recent months has revealed that the popularity of used diesels does not extend across the board. Despite an impression sometimes given in the press that diesels in general can do no wrong, demand does vary according to manufacturer and model.

I have recently been presenting our findings to audiences around the industry and they make interesting reading. The UK and Europe has seen a massive and continuing growth in new diesel sales, spurred here in particular by the advantageous benefit-in-kind (BIK) tax rules. This in turn has sparked concerns over the risk of oversupply in the used car market, where the BIK rules no longer apply to stimulate demand.

Although no slowdown in used diesel demand has been detected, a look at current demand, by manufacturer and model, gives some pointers to the future in terms of winning and losing vehicles.

Some manufacturers have undoubtedly led the field over the years in developing a reputation for producing high quality, reliable and economical diesel engines, while others have fallen behind somewhat in this area, at least in terms of public awareness.

To test this theory we researched used car dealers of all sizes – independent and franchised – and sought to determine the difference between those customers who proactively enquire about a diesel model, as opposed to being talked into one.

Perhaps unsurprisingly, demand for used Audi, Citroen, Mercedes-Benz, Volkswagen and Peugeot was reportedly naturally high. It is well-known that these marques have long been popular for their diesel engines.

Ford, Toyota and Vauxhall were among those which were subject to a lower proportion of active sales enquiries. However, this should not be taken as pointing automatically to a fixed hierarchy in terms of diesel success. These manufacturers have certainly caught up on the technological side and some may have a strong argument that they are moving into the lead on the quality of diesel offering. But the fact remains that some of their older-technology models tend to struggle today as the public seems to have made up its mind on which models to choose in the current market.'