Diesel used car prices rise by 31.3 per cent as demand for older vehicles in the used car market outstrips supply. Vehicle auction group Aston Barclay says it recorded its highest ever used car prices in Q2 as demand exceeded supply during and after lockdown. During Q2 older used cars were the most in demand with stock between 55-78 months rising by 20.6 per cent and stock between 79 and 126 months rising by 13.1 per cent. Diesel used cars rose by 31.3 per cent, which was an all-time high at Aston Barclay.