What must be modified to make the car work on the vacuum moon surface? pressure sealed HVAC circuits? Enhancements to prevent ingress of moon dust? Other tires?
I'm no expert, but here are some thoughts I had just because I think this is a fun thought experiment.
First off, the Model S wouldn't be the ideal lunar vehicle for a number of reasons:
1) Hard (probably impossible) to get in / out due to space suits
2) Unnecessarily aerodynamic (adds weight)
3) Unnecessarily has a roof, mirrors, windshield, air conditioner, heater, 3G connectivity, sound system, etc. All of those add weight and have no use.
4) A lot of other reasons that I can't think of now...
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But, for the sake of the thought experiment, the Model S would need the following:
1) Lower tire inflation (they'd probably explode if exposed to a vacuum normally)
2) Off-roading tires
3) Raised up suspension (as much as possible, like maybe 2 feet)
4) No windshield wiper fluid at all (since it would vaporize before it hit the windshield anyway).
5) I'm not really sure how liquid cooling works (does it use some kind of AC to cool the liquid?). Anyway, it seems like the whole system would require air at some point. Without air, the battery, motor and coolant would continuously heat up until they broke. The car would only cool down through infrared radiation and through contact with the lunar surface (at night). So large heat sinks (to increase the rate of infrared radiation) would be a good modification.
6) The lunar surface is 107 degrees Celsius during the day on average (which lasts for two weeks), so the tires would have to not melt (I have no idea what the melting temp of a tire is in a vacuum).
7) The lunar surface is -153 degrees Celsius during the night on average (which lasts for two weeks), so the tires would have to not freeze and subsequently shatter (I have no idea what that temp would be either).
8) Various things in the car might not be modifiable to operate in a vacuum, like the LCD screen. A vacuum might just cause it to break. If not, the heat generated at the front of the LCD (which normally cools off due to the movement of air in front of it) might cause it to overheat and break.
9) Additional pressure sealing would probably be needed in a bunch of other places too. Possibly in the hydraulic braking, possibly in the power steering, etc.
I can't think of anything else, but if I do, I'll add to this list. Either way, it seems like as long as some necessary modifications were made to keep things pressurized, the biggest issue would be temperature. Some parts of the car would get very hot (through use, sun light and lunar surface temp) and some parts of the car would get very cold (over time in the shade and through lunar surface temp). The car would have to withstand all of this. I feel like if it did work at first, it would only work for a few miles and then stop working for temperature reasons.
Does anyone else have any ideas?
Edit: Perhaps you could solve most of these problems by putting the car in a giant pressurized insulated re-enforced transparent hamster ball (I'm guessing that TEG got a picture of one of these the last time he was on the moon, right TEG?). Then it would have air, and you wouldn't need a space suit and you could drive around all day. You just wouldn't be able to leave the hamster ball.
And it would probably end up getting really hot in there due to the heat of the battery which would heat up the whole place. You could close the doors and windows and run the AC, but that would end up generating a net amount of heat, so it would get much hotter outside the vehicle (but inside the ball). Maybe if you only drive at night the infrared radiation combined with contact with the lunar surface would cancel out the heat generated by the car, and you could drive for a while?
