Focus Fanatics Forum banner

Rear diffuser?

58K views 170 replies 39 participants last post by  Sonic_HedgeHog 
#1 ·
I'm thinking about mocking one up. It will be made from all aluminum. If I build this would there be any interest?
 
#113 ·
Is your initial estimate of 1 MPG highway impprovement holding true?


What does the front actually cover? My car has a shield under the front that covers all the way back to the rear subframe.
The front one replaces the OEM fuzzy cardboard ground effect / shield piece.
 
#112 ·
What does the front actually cover? My car has a shield under the front that covers all the way back to the rear subframe.
 
#124 ·
I'd have to show off more than the tip if I spend $500 on a system but cutting around the exhaust would probably eliminate the 1mpg increase one might see and I'm never going to win a MPG battle so it would be mostly a "looks" mod since it does really clean the rear up nice as an alternative to a diffuser.
 
#125 ·
Just returned from a trip (Tulsa,OK) and noticed on a few '12 Focus' we passed that the bottom center of the rear bumper cover (black part between reflectors) will buffet at speed (75mph+). This would seem to indicate some air is getting trapped in front of the rear bumper or isn't flowing smoothly around the 'lunchbox'.
 
#128 ·
You guys must have Focuses all over the place since I've seen 7 around here in the first month and I was never behind one much less having seen any on the highway.
I made a thread looking for other Denver focus nuts and I got one reply from a guy with a first gen and that was it so it's good and bad.
 
#130 ·
If I drive good the mpg are above 40. But it's so hard not to beat on her. I average over 35mpg driving hard all the time. Pics of the front will be hopefully this weekend. I finally found a lift that I can use. Gotta change the oil as well.
 
#131 ·
I'm thinking this diffuser might work well with the lunchbox delete and a dump or two for the exhaust [thumb]

Now, where are my big ass fins? ;)
 
#135 ·
Maybe, but I was also debating a bike rack hitch because I don't want to have to throw a bike on the top of my car. Or I could get one of those racks that you strap to the car... we'll see.
 
#140 ·
2012-Focus. So I noticed you have your car lowered. Eibach claims something like a 13% gain in fuel efficiency with their newer springs. So I'm curious on how much your lower car is effecting the good MPG #s more than what a stock height car would with your new diffuser attatched? Did you notice improved MPG's after you lowered your car and then again better mpg's after the install?
 
#141 ·
I didn't notice that much more mpg when I lowered it. When I put the front pan and the rear diffuser on is when I noticed my mpg gain.

You can always paint or powder coat these. I had no reason to do to the car being lower. You don't see them.
 
#143 ·
I like the rear diffusor but still $250 is too much for it.


Primitive sells theirs for the subaru community for $160-$190 depending on thickness and are much nicer finished.
That also looks like a lot less aluminum, which isn't cheap.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top