For the Used EV credit, the IRS states very clearly that you need to get a signed statement from the dealership that includes certain information.  Purchase needs to be from a licensed dealership or something like that, can not be a private party purchase for the used EV credit.

The two dealerships my in-laws went through had never heard of the credit.  They had no idea about the $25K cap but were happy to haggle once my in-laws pointed it out.  (I mean, they had to walk out to get their attention, but obviously they aren't paying $25,001+ if it will cost them a $4,000 tax credit.  The dealership got the point that they weren't going to budge.)

Now that they have the car, the dealership refuses to provide this tax information.  I don't know if it's worth fighting in the moment.  They should eventually figure it out and it may be easier to ask for this information at the end of the year.  Let other people fight this battle?

They are supposed to provide documentation at time of sale *and* also to the IRS.  I am less concerned about the latter.  As long as we have the documentation, is really all that is important.  

I had been thinking that it would be pretty enticing to buy a hybrid and to get this credit, for MM(19).  Something like my car, that I saved my whole life working up to and is very luxurious.  A car like that is $16,000 right now and would only be $12,000 with the used EV credit.  MM(19) has the cash for that and it would last him a very long time.  Though he has a very cheap heart and might want to go more used.  The used EV Credit will swing the pendulum substantially towards an electric hybrid.  I wouldn't have recommended before, given the uncertainty of long-term situation (how long he will be renting, etc.).  I think without a charger at his residence, the full EV would be much easier/better for his situation.  But is also more expensive.  (Easier to charge out and about, with the fast chargers.)  I just don't see how you'd ever charge a hybrid, in contrast.  But if you can save $4,000...  I've seen a lot of people say over the years they only drive in gas mode or EV mode, and it doesn't seem to matter much either way.  

But...  This whole idea is off the table until the dealerships straighten up.  I would refuse to purchase if they had no idea what I was talking about and couldn't provide a tax document.  

I figured I'd share as a warning, if you are considering the used EV credit.  Heck, this also has to be an issue with the new EV credit.  This is a dealership that sells brand new EVs.  So they have to be giving new EV buyers the same runaround when it comes to providing tax documentation.  If not, they would have any clue what we were talking about.