you ain't gonna get a new merc at that price, so i'm assuming you are talking about the older stuff, but you can find 5 series td's about for well within your budget, plus it's a big car with plenty of space and if you find an estete it'll fit the bill perfectly

or you can look at an a6, but the badge snobery that goes with it will mean it's going to cost more than the equivalent bmw

as for smaller sportier cars, insurance will be the biggest factor here