With some ground rules being:
4 Seater mass market car.
Production car (aka, its going to need some cooling/heating, reasonable traction and braking and so on)
Driving solo on an existing interstate (no drafting, or crazy infrastructure enhancements)
70 Mph, 70 degrees out, no wind or rain.
2030 Production year (somewhat arbitrary, but beyond that the ability to predict what might happen is very poor)
Currently a Model S uses
~340Wh/mi under these conditions.
Therefore based on the Tesla provided graph in posted by Doug in #19:
Aero = 150Wh/mi (
based on C&D's estimate of 14hp)
Drivetrain = 115 Wh/mi
Tires = 70 Wh/mi
Ancillary = 5 Wh/mi
To get to 200, you're going to need to improve all these, so reasonable improvements would be:
Aero, increase Cp from
0.24 to 0.19. I personally think even this is a stretch, as you'll still need things like heat exchangers (for AC and drivetrain cooling) and a usable trunk which are going to make even that 0.19 number a stretch. Also assume its a smaller car, so the frontal area from 25.2 to 20. Thats rather unrealistic as well, as its the same as a 2001 Honda insight, which was a tiny 2-seater. Both of these result in 94.2 wh/mi
Drivetrain, you're not going to get much more efficient than the Model S's drivetrain. There aren't a ton of gears in it, being a single speed transmission. the Drivetrain number is based on a RWD Model S 85, so switching to the smaller front motor in the D gets you 4% (based on the difference between the RWD and D models) So maybe you could go smaller still, get another 4%? Still, not a lot of room for improvement there. Maybe put one motor per side to do away with a differential? (course then you lose efficiency by needing two motors) Still, lets be generous and give it 25% resulting in 86.2 Wh/mi
Tires,
Bridgestone committed between 2005 and 2020 to gain a 25% reduction in rolling resistance. Thats 1.7% per year, lets say they actually make that (Seems highly unlikely as they are already 10 years in and have only gotten 12%), and that they could continue that pace (even less likely as gains become harder and harder to make over time). That results in a 25% reduction to 52.5 Wh/mi
Lastly Ancillary's. Not going to be a ton of room for improvement here, but its small enough to not really effect the anwser, so lets just say a 50% drop. that means just 2.5Wh/mi
Grand Total: 235Wh/mi. So to review, if you make a bunch of extremely aggressive assumptions, and then assume they are
all able to happen, you still end up way short.