Overview: Jeremy Clarkson investigates the practice of “car chipping” by which computer boffins give a car a boost by reprogramming the engine management chip for speed rather than fuel efficiency. For as little as £200 it may be good value for money, but how will the insurance companies react, and will the engines be able to withstand it? Plus Quentin Willson reveals this year’s results in the Top Gear survey of customer satisfaction.