PROTESTS over the rising price of petrol would have a negative impact on the values of used cars, according to Glass’s, the car information service.

Fuel protests in the summer of 2000 caused a drop of around five per cent in the trade value of larger petrol-powered used cars, and Glass’s predict similar falls if there are fresh protests. Protests would also influence the types of vehicles we drive.

Jeff Paterson, senior car editor at Glass’s, said: "We are already witnessing a marked rise in the popularity of diesel cars, and their share of the total UK new car market is likely to rise further still as discontent about fuel prices intensifies,

"The growing popularity of new and used diesel cars will be particularly noticeable in the large saloon and SUV sectors where petrol consumption levels are at their highest."

Oil prices have risen by around 25 per cent since the end of 2003 and the Government have already confirmed a 1.92 pence increase in fuel duty from the start of September.

Unleaded petrol now averages more than 82 pence-per-litre and could soon reach 83.5 pence-per-litre, the level that prompted hauliers and farmers to start blockading fuel depots four years ago.