An EM thread I can have some input into
I run a 1990 big bumper Golf Mk2, which I have been attempting to improve aerodynamically. No ABA testing, but I have seen MPG improvements.
I run an engine undertray, stock VW part (well mine is SEAT) as fitted to later diesel models. Fits perfectly to the subframes, as well as blocking most of the wheel well gaps too. I will post a pic if my post count ever gets above 5
I have also installed a partial grille block, having refrained from a full block due to air cooling demands of my turbocharged engine, but all air that does pass through the grille is directed to the intercooler, oil cooler and radiator.
Also note that the rear underbody between the fuel tank and the rear valance/bumper is somewhat of a parachute, and where I'll be tackling next. Some Mk3 VR6s utilised a plastic panel there.
Look forward to seeing your progress
Kind Regards
Grant