I installed a rear diffuser on my car the other day, and its probably all mental, but I feel like the car is actually faster now. It seems to require less throttle at highway speed as well. It maybe in my head, I just wonder if adding a diffuser makes this big of a difference and if anyone else had noticed the same thing? I mostly installed it for theoretical benefits and looks but it seems to have a positive effect?!

Thoughts?

 

I don't know about faster, but I know taking a highway turn at 120mph I can feel my rear tighten up. It's nice. xD

 

^Hypermilers use it to improve gas mileage, so yes it does work for both improved MPGs and less lift since the airflow exiting out of the rear is smoother than before.

 

seems to help with high speed stabiliy on mine. maybe its in my head, who knows

 

Yeah its hard to tell. The car does feel better though. Thats the beauty of the mind!

 

Id bet unless the entire bottom of your car is flat it is just adding drag.

 

unless the entire bottom of your car is coverd up, its all in your head pal. but hey whatever works right?

what diffuser did you end up installing? just curious?

 

I wouldnt put too much money on that. I cant see how a plate that covers the entire back section of the subframe and bumper is going to increase drag. the rear bumper is one of the worst components for catching air.

Most of the underside of the car is flat, except the rear 1/3. Covering as much as possible would have positive benefits. Take the exhaust for example, it probably hangs lower than anything else, if you held a piece of 2" pipe out of the window of your car at 70mph if would give you an idea of how much drag a bit of exhaust hanging down can create.

Even if it doesnt do much, it looks MUCH better. You cant see the exhaust and rear subframe when you're behind the car. Looks more finished.