Sebring Miata Aero Data Analysis: Top Up Vs Down

Published: February 2, 2018

While at Sebring I tested the aero effect of the Miata soft top being up. Sebring is arguably a horsepower track, with long straights and many low speed corners coming on these straights.

The car used for the test was a 2003 Miata with a factory LSD and Flyin' Miata Tokico suspension on 225/45-15 Nitto NT01 tires. The runs were back to back early in the day. The first run was with the top down, the second run was with the top up.

Green is with top down, red is with top up:

The car is faster with the top up, by about a second. I wasn't completely consistent in the corners, sometimes being faster in the later session and sometimes not, but overall it looks like the speed difference due to cornering speeds is largely a wash. The speed difference at the ends of straights is about 3 mph between the two configurations.

At 3.7 miles, Sebring is a long track. Shorter tracks will see less of a difference.

The one second of lap time isn't significant enough for me to run the car with the top up, or with a hardtop. I imagine having a hardtop would provide some aero advantage over having the soft top up, but I think the difference will be much less compared to soft top up vs down. I will continue enjoying driving my convertible Miata.