It’s important to make sure a parking space can accommodate any type of passenger vehicle. Ideally, you should to be able to park a vehicle and have 60” of clearance beside it. A minimum width of 11.5’ is a reasonable guideline. As far as the length: no less than 16’ – and go beyond the minimum if feasible.
People need room to move around. You’ll want enough room to access the front and back of a vehicle, whether to get inside to load/unload items or to perform basic maintenance tasks. If you want storage in your garage as well, make sure to plan accordingly.