Aerodynamic Mods i-Miev/ion/c-Zero

HandyAndy said:

Nice! I've rather wondered about doing the same to my Ampera - the section under the boot is a total mess, open to the 4 winds & utterly drag-inducing I suspect. But I'd have to be sure not to obstruct my exhaust pipe !!!!

Did you see the recent threads elsewhere showing huge improvement to Leaf range when smooth dish-like wheel covers were used ? No idea what yours are like, but could be more miles to be had cheaply! See here...
EV News rides again!

At the back of my head I've got an ancient memory of some university students doing a drag-reduction exercise on something like an Allegro, that era anyway. They taped door gaps, added little fins to reduce vortex creation, and made a huge difference for not much effort.

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I think good underbody aero is a must for electric cars as there is literally no reason for it not to be completely smooth. It is definitely cheaper for manufacturers to improve simple aerodynamics than it is to add another 1kwh of battery.

My car has these alloy wheels fitted. I think as a starting point I will cut some coroplast plastic to fit the recessed face covering all the holes and zip tie in place.

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Aerodynamics for the maker is always a compromise. Going back to the 40s Moon discs have been fitted to custom vehicles both as an aerodynamic and style feature. But they also have the effect of mucking up the irflow around the brakes. BAck then they swapped in finned alloy drums, which probably negated the disc function. Discs have the potential to hamper brake function at the hot end of the operating range. Again not such an issue unless you are doing lots of high speed or heavy braking. The traditional mounting is small tabs either welded to the rims or even pop riveted to the edge of the rim and dzeus fastners then holding the disc to the wheel. Not something you should do to a modern wheel. Also likely to be expensive when you hand it back after two or three years of PCP. Cable ties just dont look cool.
Underside body trays can make a huge difference. But often only at certain speed ranges. They can also upset airflow for cooling, but again this may only happen at certain speeds. And punching louvres can help. Blocking airflow if there is an upward exit should be avoided as this could again at certain speeds upset downforce. Minimal, but an Insurance company will clutch at any straw. Mounting should be by Dzeus fastners or by recessed fixings to really do the installation justice.
Simple things like using a stick on vinyl front number plate, removing a tall aerial are all ways of reducing higher speed drag. But frankly you will get more effect by either increasing tyre pressures to the max that the car is rated for, or changing tyres for the narrowest its options allowed, or going for the most eco version that fits . But any change will have its impact. Eco tyres also tend to have less grip. Higher pressures will give a harder ride and possibly reduce traction with a smaller footprint.
Most makers under trays are made from something like high density poyethelene, Doesnt look as good as alloy sheet, but if you hit it, the damage is often less and if itgets caught its more likely to tear and do less damage than a sheet of alloy getting ripped off and squished under the car. Not a great concern for a race car, but could be for the car following hitting the debris. Smaller sections also lessens the potential issues of under trays coming away at unexpected times.
Great fun and an interesting project.