What about a Saab. Admittedly the newer ones are based on Vauxhall, but if you get a petrol then the engine is Saab (which is a very good thing).
Serviced, they will go on to the end of time. A lot of people who look after their Saabs get 200k plus miles out of them. I bought a 90k car for £1300. Air con, 10disc changer and a 2ltr turbo. Imaculate condition. Returned about 30mpg, had grin inducing acceleration once the turbo was on boost. Made for safe and fun overtaking.
Apart from me giving it oil and air filter changes in the 30k miles I had it for, I did nothing else to it and it passed it's MOT's fine.
Near enough anything will return 30mpg plus if you do a lot of motorway miles and don't have a heavy foot.