I get 30mpg from my +8 when touring but I have heard that you can get over 40 from the newer 4/4s. If 2 or 3 year old cars are the same price as new basic models I would try and spring the extra and get a new one speced to your needs.
Nothing beats the design process or the bitter sweet wait.
(But I would suggest looking at +8s, future prices are hard to gauge but I would expect the +8s to be depreciation free, ignore obvious bias)
