New car buyers can get the biggest savings off list prices on diesel cars according to the latest research by Britain’s leading consumer champion and new car buying platform, What Car? Analysis of the UK car market by What Car?’s Target Price mystery shoppers found the average discount on a new diesel car at the beginning of March was 7.82 per cent off the list price, or £2731. Discounts on diesel were only marginally higher than for petrol models, which stood at 7.11 per cent or £2101.