Rear Glass - With our without


Does anyone know of any handling differences with the rear side windows and rear window removed vs. installed?


We had a Lemons car with no rear or side windows. The glass is pretty heavy so it’s removal means a nice loss of weight and lowering of center-mass. I can’t say for sure I really noticed a handling difference. What I really noticed was a visibility difference. Somehow, and I never did understand why, the absence of the windows made me much more aware of the traffic to the sides and behind me.

Those that ski will understand an analogy of skiing with goggles or skiing with glasses. Goggles kind of make you feel “remote” from your surroundings. It’s easier to be “in tune” with the slope, your balance, and your ski’s edges when you’re wearing sunglasses vs. goggles. It was a big difference, at least to me.

Of course it’s not SpecE30 legal.


It is legal if you have a 4 door. The following interior components may be
removed: carpeting, seats, headliner (to
include the leading plastic panel), console, radio/
cd/cassette/navigation/trip computer
systems, OEM seat belts, speakers, glove box door,
panels under the dash, grab
handles, [color=#ff0000]driver and passenger door (front and rear)
window glass and mechanisms,[/color]
heating and cooling system interior ducts, rear pas
senger compartment trim panels (side
panels and fabric package shelf) and sun visors. Th
e third brake light shall remain in
place and a custom bracket may be used to secure it
to the steel package shelf.


Just ran a chump race in an e30 without glass, Scott is right about the feel, about like running an open car.



Wouldn’t that create massive drag at speed?


Hard to say. It takes a lot of experience to gain good intuition on aero stuff. With a complicated structure, often the book learning can’t be relied upon and the structure has to be tested.

The loss of the rear window prob won’t cause additional separation to the air flow going over the car. Air rushing in the cabin and out the rear window tho, could reduce the low pressure zone at the rear window and add to efficiency.

Air blasting into the inner C pillars can’t be good. Air going around the sides could be more chaotic with the loss of rear/side windows, or it could end up more clean because a lot of air will turn in and exit out the rear window. Then you’ve got the B pillar right in the air stream.

I’m an ME, not AE. I can’t even guess which of the variables will dominate the result.


Thanks for the suggestions everyone. We have a 4-door Chump/Lemons E30. The cage of our prior 4-door E30 did not allow much accessability through the rear doors to store tires and fuel jugs so we had to go in through the rear window. Our new car allows a set of 4 tires and our fuel jugs to be stored when accessing through the door. Hence is why we are now considering to block off the rear and rear side windows with 1/8" Lexan. It appears more Chump/Lemon cars are doing this.