New beetle tdi 5 speed

[freebeard]

Have you trimmed it back yet?

You could decide the shape before you move on to new materials. Simple curves are easy, compound curves are more efficient.

Stitch-and-glue plywood, or Polymetal composite, less messy than fiberglass and foam.

[aerohead]

It looks like something made to 'sell', which has nothing to do with aerodynamics.
Ernie's 'Beetle Wing' will be the better investment.

[COcyclist]

Originally Posted by NeilBlanchard

I thought that the new Bug had a Cd of 0.45? The curve in the rear is way too steep. I doubt it has attached flow as far down the back as the picture shows...

Welcome razordave. The New Beetle has pretty poor aerodynamics as you are aware. The biggest problem is the rounded roofline leading into a too steep back glass. I am including a drawing from another thread. It shows attached flow all down the trunk. What it doesn't show is the two counter-rotating vortexes coming off the C pillar. That is where much of your drag comes from. I think your Kammback is a good start if you can make it strong enough for everyday use.

FWIW, I tuft tested my windshield and the air flowed down and forward where the wipers are. I don't think you will notice much difference by covering the cowl or removing your wipers.

[razordave]

I believe the response I saw to that particular drawing was doubtful.

I finished a bunch of mechanical work on the car and the result was +2 mpg.

Could have been egr delete and straight pipe? I have all new brake calipers and hoses
That still need installed but hopefully I'll be able to get back to aero mods.

I also added instrumentation.

[COcyclist]

If you do the EGR delete, make sure you set aside some time to do an intake manifold cleaning. I made it to 110,000 miles before I did mine but it was a mess.