This varies, depending on where you drive the vehicle, at what speed, and how stiff your suspension is. Some show cars are never driven anyways, so they can go down to less than a millimeter above the ground. If you cruise at low speed in town on smooth pavement and have stiff suspension, you might get away with 1 inch, though I'd recommend at least 2. If you can go down to 1 inch without body damage, your suspension is probably so stiff that you wouldn't want to ride in the vehicle for more than a few minutes. If there are ANY potholes, cracks in the pavement, speed bump etcetera or you plan on travelling at highway speeds, don't go lower than 3 inches. And if you're driving in my area, don't go lower than stock ride height. I see so many cracked bumpers and side-skirts that I just have to shake my head. Oh, and forget about taking the car out in the winter. The last 2 cars I drove that had any sort of front airdam were 5-1/2 inches off the ground, but just piled snow in front of the car instead of letting the car drive over it. After spending 3 hours digging one out last time, I just ripped off the lower lip and never got stuck again.