What car/truck has most head room? most seat width? back seat leg room?
The way to find out is pick vehicles, specific vehicles, you might be interested in let's just say Lincoln Town Car. Google "Lincoln Town car" and when the search page comes up click Edmunds .com and look at features specifications
As an example: 2013 Lincoln Town Car: Interior Measurements FRONT HEAD ROOM 39.4 in. FRONT HIP ROOM 57.0 in. FRONT LEG ROOM 41.7 in. FRONT SHOULDER ROOM 60.3 in. REAR HIP ROOM 58.3 in. REAR HEAD ROOM 37.4 in. REAR LEG ROOM 45.4 in.