> a big carbon-fiber pressure vessel at 5500psi

Other cars have these tanks, but full of flammable fuel, not just air.

Off the top of my head, the honda civic CNG (3600 psi)

https://en.wikipedia.org/wiki/Honda_Civic_GX#Specifications

the toyota marai (10,000 psi hydrogen)

https://en.wikipedia.org/wiki/Toyota_Mirai#High-pressure_hyd...

and probably the other cng or hydrogen cars.