Okay...I am a total newbie, and just got my '92 VX...on my first tank of gas and starting a fuel log. I'm also considering doing the grill blocking trick to boost the mpg some. This may be a dumb question -- but I was considering putting some of the OEM mudflaps on the VX and wondered if this might be an aerodynamic no-no? Anyone had any experience with this, or is it truly a non-issue?
Mud flaps will likely cause a small penalty. If it's not large and you want to know exactly how much, it will take extensive testing to measure.
If you wanted to do something a little more out-of-the-ordinary, search the forum for posts about wheel deflectors where people have used mud flaps as part of the system. The idea is to make the entire system into an aerodynamic teardrop shape; first you control how the air hits the front of the tire, then the mud flap is kept very close to the tire so air can't get between the tire and flap, and then the flap is followed by the rest of the teardrop...that kind of system may improve fuel economy, and also provide you with mud flap-like protection.
Ah...also saw there was a thread on this back in 2005. Thanks for the ideas about thise, they are the small OEM flaps and keep (some) of the road crap from hitting the lower body work, but hopefully wouldn't be too much of a hit aerodynamically speaking. Wheel deflectors are a very cool mod -- but a bit beyond me right now! Still trying to figure out how to do the grill blocking and have it look decent too. Yeah, I know - I'm a girl.