I got a 3 year old Passat TDI 140 SE 6-speed manual for £6k with around 70k miles on it.
Has been excellent in every way, provided you accept that it's never going to be a sports car, and handles more like a marine vehicle than a car.
Decent legroom and headroom, boot space is all you'd want. Great on the motorway, 50+mpg as an average, has been totally reliable over 40k miles. Cruise, Xenons, aircon, reasonable stereo, leather seats, quiet-ish, and dead comfortable seats. Did an 800 mile day recently and it was fine, if dull. The engine has a bit of poke to it between 1500 and 4000 rpm, nothing much above or below. Cheap to insure.
Only slight problem was initial very high tyre wear, but after getting all the wheels properly aligned, that went away.
It's really boring, mind you.
Different trim levels – just more kit (multichanger CD, climate control rather than manual aircon etc) rather than anthing else, though the Sport has firmer suspension. They pretty much all have the same engines AFAIK.