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Old 03-07-2019, 10:24 PM   #6 (permalink)
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There's an aerodynamicist for one of the OEMs who posts occasionally on Jalopnik and TTAC; according to him, mudguards are always a drag hit, so I would remove those first. Also according to him, air curtains on the front wheels are usually worth about -.005 CD; you could use the fog light blanks as intakes for these and then crib the ducts off something like an Ioniq for less than $15.

Get rid of the exterior mirrors and their associated interference drag and frontal area; you can remove both legally in Ohio. Replace with something like this:

...or cameras if you feel like and your budget allows.

If you don't have grill shutters (I don't remember if the Mirage does or not), block as much of the grill as you can without affecting coolant temperatures. Scangauge, Torque or similar will be useful to get accurate temperatures directly from the OBD.

For improved lateral stability, I would try something like what Toyota does, with fins on the underside of all their cars that they say specifically improve highway stability. Here they are on the rear diffuser of the 2020 Corolla Hybrid:

Toyota has switched to a 4-fin design from the earlier 2- found on the Sienna, Prius, etc. This is something you could model in CAD and test size/placement. Similarly, if you end up adding any sort of spoiler extension, you can add stabilizing fins there as well, like Lucid did on their record car:

Any tapered extension you add at the rear will likely reduce drag; again, something you could model in CAD and test.

If you can get a copy of T. Yomi Obidi's Theory and Applications of Aerodynamics for Ground Vehicles (you can find it on Amazon), it has an entire chapter on vehicle stability you may find useful, in addition to the rest of the book which is quite thorough.

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