Looking at changing my car. £5000 budget. Want a saloon car and not had a BMW before. Looking at 2007/08 models with about 50k miles for that sort of price but can anyone tell me the difference between 318d and 320d models. Seems the 320 has more bhp.......is there much difference in mpg? Which is the better version? I do about 14k miles a year, mixture of local and motorway. Any advice appreciated.