Your budget isn't enough to stretch to the high-end cars like Ferrari, and a modern classic within your price range needs to be a sports car if it's going to hold it's value - which excludes your criteria of it being a family car, and being inexpensive to tax and returning decent mpg. Perhaps something like a Renault Avantime would fit the bill? It's definitely a future classic and more than capable of moving the family. Failing that, there's a strong following for Land Rover, so a Defender might work - but it will feel very agricultural compared to your current vehicle. If you need something more middle of the road, try the new Ford Fiesta ST (although you'll have to ride the depreciation curve) or try and jump on the hot hatch wagon, with the Golf GTI or 205 GTI looking like good bets for an all-rounder.