How much are they wanting to discount it for the mileage?
I don't know about anywhere else, but in FL they do that by dividing the actual mileage by 120,000. In other words, if they were buying it back and it had 60,000 miles on it, they would knock 50% off their buyback amount.
Also in FL, they REALLY do not want an actual Lemon Law filing against them. So, if you talk to them about a buyback before filing any Lemon Law paperwork, they tend to be a little more amenable to negotiation. But, once the first LL paperwork is filed, the damage is done and then they are going to go strictly by what the law says. However, generally, their initial offer is going to be what the LL dictates.
I just think it's kind of funny/sad that the FL Lemon Law basically has it enshrined in state law that any and all new vehicles are deemed to be worthless after 120,000 miles.