2. What the tortfeasor (at fault driver) owes you at law. In negligence law,
damages are compensatory in nature and as such the award should make the plaintiff whole, sufficient to put the plaintiff back in the position he or she was before the defendant's negligent act. Anything more would unlawfully permit a plaintiff to profit from the tort. That is not allowed.
Arguably, the OP renting a Model X while his is being repaired does not mean he is profiting. Rather, he is simply attempting to be put back in the position he was in before the defendant's negligent act, and while his vehicle is being repaired. As such, he could pursue the at-fault driver for those costs, since renting that X during repairs simply put him back in the position had the negligent act not occurred.
Sorry. I've been through this in the USA with a lawyer. The USA does not recognize loss of use on a pleasure craft. An at-fault-party doesn't need to compensate you for loss of use on a vehicle that is not operated for financial purposes.
Thus, the only thing an at-fault party is liable for is making sure you can still get to and from work in your vehicle as that was the financial use of the vehicle. This does not require a specific vehicle.
The Conqueror, 166 U.S. 110 (1897) involved a yacht purchased in England and brought into the United States by a United States citizen for private pleasure use. The yacht was seized by the United States Treasury Department on the ground it was subject to taxation. The yacht owner sued to regain possession of his vessel, and for damages. The district court ordered the return of the vessel to its owner and awarded the owner $15,000 in loss of use damages. The court of appeals affirmed. The United States Supreme Court affirmed the judgment ordering the return of the vessel to its owner, but reversed the award of loss of use damages. It held there must be a pecuniary loss to the owner of a private pleasure vessel or a reasonable certainty of a pecuniary loss to justify an award of loss of use damages. The court noted: 1) the vessel was purchased for the owner’s personal pleasure; and 2) there was “not an atom of testimony” tending to show it was purchased for hire or other commercial purposes.
So basically, you are "made whole" if you get your property back in as-before condition, and if you suffered no other financial loss. As long as you could still get to and from work, you're compensated.
Seriously- I almost sued over this. I had a race car on a trailer once and was rear-ended on the way to the track. The race car was damaged. I didn't get to race it for months in the short summer season. Under US law, I wasn't owed anything as I raced only for fun, not for financial gain, and thus as long as they got me the car back then I was "whole." They didn't even have to reimburse me for the track fee I had pre-paid and didn't get to use that day. There was no way to recover the loss of use for those months, and if there was a way to rent a race car, they wouldn't have covered that. Only my direct losses were covered.
Maybe I had an atrocious lawyer, but looking at the case law he referenced it was pretty clear to me his analysis was reasonable.