A ROW has broken out over a claim that a servicing timebomb could be ticking away in hundreds of thousands of diesel fleet vehicles because of drivers' ignorance of the vehicles' maintenance needs.

The Retail Motor Industry Federation (RMI) has issued a bleak warning that many diesel vehicles coming up to three years old may need professional attention to get them through their first MoT test.

Fleets are taking on record numbers of diesel vehicles and the RMI believes motorists may not realise how much attention diesel vehicles require in comparison to petrol-fuelled vehicles.

But the claims have been dismissed as scaremongering by the Society of Motor Manufacturers and Traders (SMMT), which says most vehicles would be serviced by RMI members anyway.

Ian Davis-Knight, RMI head of MoT and technical operations, said: 'Diesel vehicles need constant professional attention to ensure they run properly. More diesels than ever before are going to be taking an MoT test in the next year, but many motorists may not realise that diesel cars need special care.

'To get through the MoT test, a diesel vehicle will need to have been maintained correctly.'

Part of the examination for diesel vehicles will be an emissions test. This will involve measuring the smoke emissions from the exhaust while the engine is being revved up to its maximum governed speed.

According to Davis-Knight, this could damage a vehicle if it has not been well looked after: 'This test will not harm an engine that has been serviced and maintained correctly. 'However, if this is not the case, and the camshaft drive belt has not been changed when required, there is a possibility that damage will be sustained.

'The tester will not carry out a test on the vehicle if assurances on these points are not received. If the belt has not been changed, it is advisable to have it checked and replaced as recommended by the manufacturer.'

A spokesman for the SMMT said: 'Every vehicle requires regular servicing in order to run efficiently and have the minimum impact on the environment.

'This applies whether it's diesel, petrol, liquefied petroleum gas or compressed natural gas, and manufacturers state quite clearly what is required at each service.

'It is surprising for the organisation which represents the dealers who sell these vehicles to be suggesting that somehow diesels are at greater risk than petrol – it's just plain wrong.'

'Scare stories are probably not the best way to drum up service business – the facts are that well- maintained vehicles retain their value better, cost less to operate in the long run, and also do less damage to the environment.

'With regard to the fleet market, diesels certainly do have an advantage over petrol in holding their value in the longer term, but there is no evidence we have seen to suggest that they have any greater risk of failing an MoT than other fuel types.'