Here it is again. 6' ceiling. 7'4" total height.A vehicle fits in a garage because you sit down in it. If you had an RV that fit in a garage, you wouldn't be able to stand up in it, which I assume you'd also complain about.
You fit into your Chevy because you're sitting down, not your garage. Your garage door is probably 7'6" high. Your garage ceiling is probably close to 9'. Andre the Giant could walk under your garage door without hitting his head. He was only 7'4".