Hey everyone been lurking here for awhile now and thought I'd share something interesting that I have made. In an effort to reduce drag and increase gas mileage I ended making functional rear bumper vents for my Mini. I found the fake aero that BMW gave us to be a bit on the ugly side and who could really say no to better mpg, right? Here are the stock solid pieces of vents that are faker than my blue Supreme sandals.

First things first, popped them off but low and behold...there's and exhaust shield...great. SO MUCH FOR FUNCTIONALITY

I should have just stopped here and given up. But no, I wanted the functionality, I wanted to gain .000000005MPG on the highway @100mph and I wanted to get rid of the solid pieces disappointment that were my fake vents! So I unleashed my inner Clarkson and cut the exhaust shield with a hammer. Am I doing this one ball exhaust mod thingy right??

Finished cutting off the shield and hammered the rest upwards and out of the way. Also sprayed the remaining shield and muffler with black high heat spray paint to make the exhaust quieter and less droney. Now that I think about it, I probably should have painted everything red, I would have gained at least 15hp and gotten a louder exhaust.

Isn't it beautiful? Paid $150 for these authentic blue Supreme sandals.

I've had these on for about two weeks now with no issues. At first I was worried about cutting the exhaust shield and it melting everything, but after my rear bumper caught on fire and everything burned to a crisp it never caught on fire again, problem solved. I also noticed my MPG improved drastically it went from 27 down to 13!!! I go to the gas station about once every 3 days now and I'm definitely getting my money's worth from my Costco membership.

But on a serious note..maybe... car def looks uglier now. Okay but for real, I have not really checked my MPG but from basic aerodynamic principles I am sure it has to have improved no matter how minuscule. Car seems a little bit quieter, maybe its in my head, but there is less drag and no more rear bumper parachuting effect....orrrrrr....maybe its the black spray paint.. who knows?
Lastly, I am making another set for a friend since I have material left over and I have enough remaining to make a handful more. If anyone would want a pair of these bad bois to spice up their love life I wouldn't mind making a few more. Which..if I do? Do I need to register as a sex o vendor? HAR HAR...that was a terrible joke. I'm sorry. Thanks for reading my post and I hope you enjoyed it!

 

Funny, I've been under the back of my 05 on and off for the last coupla days.
I noticed that the heat shield was tucked up about 1-1/2" from the bottom of the bumper cover. Leaving 1-1/2" of scoop to catch air and swirl it around between the heat shield and the bumper cover.
Unlike what you did, I pulled the heat shield down far enough so that much less air will get between the two parts and act like a...parachute..!
So rather than letting it out thru the vents like you did, I just forced it straight down past the bumper cover/parachute into the after car air-stream. Since the heat shield is a solid part, from the floor down, the air flow shouldn't be too badly mixed up, being that it's a smooth, flat panel, all the way across the car.

The "proper" way would be to attach a piece of thin aluminum sheet, from fender to fender, and from the floor behind the axle assembly, down and back to the bumper cover.
Actually from axle to axle, the little Mini isn't TOO badly smoothed/streamlined. A little work there would go a long way toward mileage, additional speed. Cap of the rear like I described above...
Bonneville here we come..!

Mike

 

Did you buy those grills? Or cut out each individual hexagon with an exacto knife?