Car’s Underside / Belly Pan - Make it Aerodynamic
The underside of your car is one of its most aerodynamically dirty areas. Most vehicles will benefit by fitting a smooth undertray - something manufacturers are doing more and more where they want to squeeze the most efficiency from any particular model (eg. Jetta diesel vs. gas; Camry hybrid vs. non-hybrid).
Sheet aluminum or corrugated plastic will do the trick. Just make sure that you don’t put any flammable materials near hot exhaust pipes.
Click More To See An Example:
From the Australian web magazine Autospeed -
Some of you may have seen these already…
Originally these articles used to be pay-access only, but they’ve opened them up for public access now.
The project documents the creation of a prototype front partial undertray for a 1st gen Prius, testing, and then fabrication of a permanent version.
Before:
Mockup:
Final version:
The writer reports a 10+% improvement in fuel economy at freeway speeds (100km/h) with the mod in place. I frankly find that a bit difficult to believe, though I don’t doubt there was some improvement.
If you read the article you can find a few holes in his testing approach - even though he’s fairly aware of things like experimenter bias, and aiming to perform tests on the same day (for consistent weather conditions).
The articles also give a good background on the subject of under car aerodynamics. Definitely worth a read if you haven’t seen them yet:Modifying Under-Car Airflow, Part 1
Modifying Under-Car Airflow, Part 2
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