It is widely reported that the Aero wheel hubcaps increase performance by about 4%.
Whatever the improvement, it is more useful to talk about the
Wh/mi improvement provided by the aeros at a
specific speed than a %. This improvement, specified in Wh/mi at a certain speed, should be roughly the same regardless of exact Model 3 vehicle.
The reason it matters is that the aero wheel covers:
1) Provide minimal benefit below 40-50mph. Because aero just is not that significant there.
2) A % does not take into account whether the vehicle is RWD or AWD. A RWD vehicle will see a greater % improvement in efficiency due to its overall better efficiency. This means the aeros will buy you a few more miles of range in a RWD than an AWD.
3) Related, in winter time, these things matter even less. If your baseline consumption is more like 300Wh/mi in mid-winter because you're trying to stay warm, or are plowing snow with your tires, or you have studded tires (or performance tires!), or it's raining with a blasting crosswind, the aeros start to matter a
lot less. They still help no matter what, of course.
Keeping the Wh/mi number (at a certain speed!) in mind allows you to determine the efficiency improvement more easily for a given set of conditions. (You can memorize a couple different speeds or just roughly scale that baseline number by (v2/v1)^2 for other cruising speeds.)
Based on above posted non-scientific tests, it does seem most likely that the improvement is something less than 10Wh/mi @70mph, but that's not nothing. Might be 15 miles of range improvement for an LR RWD vehicle at that speed (but again, the gain in miles depends on the efficiency being achieved for that drive!).
