When Renault increased the power of its 1.9 diesel engine from 120 to 130 bhp they put a particle filter in the exhaust system to clean up the emissions. This meant the service intervals increased from 18,000 to 9,000 miles. Special oil has to be used, which costs £50 for 5 litres. But worst of all, if the car isn't used on regular long journeys or you don't take the car for a long run at high speed when the 'Particle Filter' warning light comes on, the car locks down to 3,000 rpm. This means that you have to take the car to a Renault dealer to have a £300 procedure carried out to clear the filter. If this doesn't work a new filter costs £1,000. Yes that's right, £1,000. Plus fitting. I know because I bought one at auction without knowing any of this. Luckily I managed to return the car when I found out it was put into the auction against the auction company's terms. As cars with particle filters come out of warranty the situation will come into focus more and I hope the outcry force manufacturers to sort this out.