Ideally, parking lots should be rectangular with parking on both sides of access aisles. For two-way traffic flow, parking spaces perpendicular (90 degrees) to the aisles provide the most efficient design.

In terms of land use and spatial density, automated (robotic) parking systems are the most efficient. These systems use mechanical lifts and pallets to "stack" cars in a solid block, eliminating the need for driving ramps, passenger elevators, and pedestrian walkways within the storage area. Because no humans enter the parking zone, the ceiling heights can be much lower, allowing a robotic garage to fit twice as many cars as a traditional garage in the same footprint. If we are talking about surface lot design, angled parking (60 degrees) is considered the most efficient for traffic flow and ease of use. It allows for narrower driving aisles compared to 90-degree perpendicular parking and reduces the turning radius required to enter a spot, which minimizes congestion and accidents. However, for sheer "capacity per square foot" in a standard open lot, 90-degree parking remains the winner, provided there is enough space for wide aisles. Urban planners also point to "parallel parking" as the most efficient for narrow streetscapes, though it has the lowest density and the highest impact on traffic speed during the parking process.