Residual values can be affected by many factors but the ones that seem to be overlooked by most manufacturers are confusion and misunderstanding.

Many carmakers have model ranges that mystify and bewilder dealers who are not directly linked to the franchised network, let alone the motoring public. This can have a major effect on residual values when these vehicles leave the closed auction arena.

They invariably end up offered in part exchange, or sold at open auction to dealers who do not fully understand the specification or the value of the car.

In these circumstances the dealer, out of lack of knowledge, usually under-bids. This scenario, if repeated all over the country, will have a negative impact on residual values.

This situation is not helped by the problem of badging. Where the equipment level is not made clear from the car's badge, it can leave dealers in doubt. They will assume the worst and the price offered will be that of the lower spec model.

Equipment levels are increasingly vital in the used car market; rising customer expectations mean that only cars with the right specification are really sought after.

Obviously dealers can see if aircon and leather seats are fitted but when it comes to different engines or ABS it is as well to make the better equipped models stand out to ensure that they achieve the best possible residuals.

Manufacturers try to cater for every taste and budget, but where this becomes excessive it results in confusion and a loss of interest.

This is exacerbated by the wide range of names used by carmakers for varying specification levels.

For example, Renault has Authentique and Expression; Vauxhall has Club and Comfort; Mercedes has Avantgarde and Elegance.

Honda seems to be moving in the right direction with the Civic, a concise range with 17 models. Once wayward but now reformed is Ford, with 48 models in a comprehensive Mondeo range. Some of its competitors could take note, as they have similar ranges that consist of more than 100 models.

Higher up the scale the Mercedes C-class has 76 models, without including coupe or AMG derivatives. Other manufacturers change model names and line-ups mid stream, or have ranges with a mind-blowing choice of engines. Even more of a worry is the option of low pressure or high pressure turbochargers which are differentiated by a lower or upper case 't'.

The big T, little t syndrome is where company car drivers fill in their vehicle preference forms only to receive the wrong car because they jotted down the wrong type of 't'. So with all this confusion, it really is time for some clearer and more concise model line-ups.