It is believed that the problems suffered by thousands of motorists over the south-east may have been caused by petrol contiminated with silicon.
Thousands of motorists have experienced problems with their cars after filling them from a number of petrol stations in the south-east.
The cars have suffered from pinking and stalling, and many have had to be taken to garages on recovery trucks.
Garages have said that the cars have suffered problems with their lambda sensors, which measure the exhaust gas mixture and control fuelling.
One of the main ways to irrepairably damage a lambda sensor is for it to come into contact with silicon or silicates. Early reports from the AA say that petrol from affected cars shows traces of silicon - which is sometimes used as a lubricant in petrol, but should never be found in the quantities discovered.
There is a chance that the petrol has been inadvertantly blended with too much additive. Silicates are also often used as corrosion inhibitors in anti-freeze. It is possible the batch of fuel which has caused the problems has been inadvertantly contaminated with anti-freeze.