[AeroModder]

After driving through another tank, the difference with the completed undertray and diffuser, and driving 10 MPH slower on the highway, only showed a 1 MPG difference, which is within a margin of error.

Needless to say, this is very dissapointing.

At first, I thought this may be due to some kind of mechanical issue. When attempting to inspect my catylitic converter (since it is 18 years old), I noticed water pouring from the air hoses. I'm wondering if it is partially corroded on the inside, and may need replacing.

However, after a more critical inspection of the undertray, I've found a place that is most likely catching air and creating drag. The bolts had loosened up somewhat, so I retightened them and did my best to seal off that area.

We'll see what happens with the next tank, whether the issue is mechanical or aerodynamic. Any advice would he helpful.