My husband is 6'6" and for comfort and proper posture, we have had a Jeep Wranger, a VW Passat without a sunroof, a Ford Expedition without a sunroof and our next vehicle will be a Chevy Suburban without a sunroof.
We started out at a car show and had him sit in every vehicle we thought he might fit in. He did fit well in one of the Land Rovers, I think it was their biggest one.
When trying out the cars, make sure the seat is all of the way down towards the ground. We rent cars for the weekend and see what we think, rather than buying a vehicle and hating it.
We found that the Toyota Landcruiser, etc had barely enough room, but not enough room for the kids legs in car seats behind him, let alone a full-sized adult.
My SIL is 6'4" and drives a Passat with a sunroof.
Our neighbor loves his Dodge Sprinter and there is PLENTY of room in there. We considered getting one, but we take lots of road trips and when it gets windy, we didn't want that extra height to contend with.