At What Point Does A Lowered Car Hurt You?
 

Ive been wondering if there is a general rule on the aerodynamics underneath the car. My car sits about 4"-4.5" off the ground, and Im wondering if that may be a problem, or hurting my mpg.

Anyone run into this problem before?

I've heard 2.7" is the optimal distance from the ground for aero, *shrug*

ground clearance
 

I know of no general rules or relationships for G.C. and aero.For street driven passenger cars and light duty pickups,auto manufacturers design in "approach,departure,and ramp breakover angles,as per Society of Automotive Engineers SAE J689 Standard.This allows a 16-degree angle at the front of the car,from the tire tread bottom,projecting up and forward,clearing just under the nose.Behind the front tire,in front of the rear tires,and also behind the rear tires,they like to see a minimum of 10-degrees projecting up to the rocker panels.Anything less,and you leave parts of the car on driveway ramps and such.High performance cars and high mpg concept cars use active suspension,which lowers the car on flat open highways,and then raises the car back up when it decelerates for regular in-town driving.4-4.5-inches sounds kinda low.You probably have an advantage right now,aerodynamically speaking.Your challenge is to keep the car in one piece.

From a custom car builders stand point, A sparking car is a happy car.

For a time I thought road reflectors were on the road to remind me to pick up my front end a bit with the air suspension ...

But I guess for our purposes, a car is to low if vital components are dragging or scraping on the ground, unless of course you alter those to go lower. :thumbup:

Yes I guess I should have been a bit more clear on that one.

"At What Lowered Clearance Does Aerodynamics Hurt Your MPG"

Thats what I figured. Although I do realize that you still want airflow under the car, but with that, how much? It is probably nothing to extreme to the point where I will see a considerable difference in fuel consumption.

I will post up a write-up on my new front skid plate Im making soon. Its going to cap off the underside of the front bumper clip. Also, I may put little fins to direct flow away from scrambling against the front tire. Would that be a decent idea? Or would that construct more of a problem?