For a single vehicle, a 12’ x 20’ unit is generally the minimum size required to comfortably park and open doors. For two cars, a 20’ x 20’ or 24’ x 24’ structure is standard. However, if you plan to perform maintenance, store tools, or add shelving, it is highly recommended to add at least 5 to 10 feet to both the width and length. Always consider the height of the vehicle as well, especially if storing trucks or planning to install a hydraulic lift.