Quote:
Originally Posted by nexus_2006
Thanks for the comparison, that is very helpful! I believe my mk6 and your mk4 have similar stock Cds (.34 on the mk4 vs .32 on the mk). Does that CFD include your underbody mods as shown in your picture, or is it for stock? How did you get the CFD analysis done?
Also, I'm a little confused about something. To reduce the low pressure behind the car, I should be looking at box cavity/flow separator kinds of shapes, right? Or should I be looking more at getting flow to wrap around via rear diffuser, slotted spoiler, etc? Or does the rear airflow really not matter at all until I get the underbody cleaned up?
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I just copy and pasted from this thread. I don't know where Jorge found it.
https://ecomodder.com/forum/showthre...mk4-37836.html
IMHO you will not see the mpg gains you want unless you smooth the underbody, fill gaps and openings and add a big tail but every bit helps.
You would probably get higher mpg numbers if you swapped the tires and rims for skinny LRR tires and slowed down 10 mph, but that's not why you bought a GTI.
P.S. If you can find a Panzer Plate for $80, grab it. That is very cheap insurance for our low and easy to crack oil pans. (Edit. I just re-read your OP and you mentioned an OE cheap plastic pan for $80)