Comfortable car help please

[TOVIK]

I am looking for a car that will be as comfortable as possible and deliver at 50 miles per gallon economy.

I need decent leg room and capable seats, because I'm 6'10" and around 20 stone plus I have a back injury.

I would like :-

Extra comfy heated seats (even better if they do some kind of orthopedic / massage magic)
Good stereo and DAB radio
Plenty of legroom
50mpg or more for a 50 mile twistyturny commute

Ideally, not horribly slow, but performance is very much second best to comfort and economy.