Piston Slap: Raising the Bar by Lowering It?

TTAC commentator educatordan writes:

I know this is an exercise in mental masturbation but I find myself thinking about it and perhaps the B&B with their extensive experience could shed some light on the subject.

OK here goes; Will lowering a vehicle improve the vehicle’s fuel economy? Several manufacturers of lowering systems claim that it will, but would it be measureable? In my mind even 1 mpg would be significant on certain vehicles. This question sprung to mind as I was looking at low resale values on fairly clean early to mid 2000s American SUVs. Those TrailBlazers, Envoys, Raineers, Explorers, Mountaineers, and Aviators are likely as close as were gonna get to a modern version of the all American family wagon and you can buy lowering kits for even the 4wd/AWD versions. I know lowering a vehicle improves handling a rollover resistance but what about fuel economy?

Sajeev answers:

I hope this isn’t an exercise in mental masturbation, as I sometimes consider this quandary while exiting the freeway in my 1995 Lincoln Mark VIII LSC. That’s because the Mark’s air compressor refills the air springs to raise the ride height 20mm when the car goes below 45 MPH. And, compared to the low-speed ride height, they drive better (variable-assist steering too) and looked pretty cool lowered on the highway…back when they were a common sight on the highway. You may not see a new “Quadra-Lift” Jeep Grand Cherokee perform the same trick, but they do.

Alrighty then! According to this thread, there can be a fuel economy benefit to a lowered vehicle. In theory. Always in theory.

I like the theory of lowering a car to reduce the “frontal footprint” of your tires. Whether or not lowering the vehicle will mess up downforce to the point of fuel economy detriment is anyone’s guess, unless you have a fluid dynamics lab in your garage. For the purposes of a street car that can be lowered enough to not ruin wheel alignment/suspension travel/load carrying abilities, I suspect lowering a vehicle will improve fuel economy.