I'm on my second demo Genesis and there was/is absolutely nothing wrong with either car.
The first one was '13 Genesis Rspec, bought it with 4600 miles on obo, drove it for 2 years, put 16k more miles (trouble free, not a single problem) then traded it in for another demo, this time for '15 5.0 with 4200 miles on obo. Both cars looked like brand new cars, no visible "use" of them.
Do I care if their weren't brand new, with just a few miles on the clock? no. In each case, I paid ~14k below the sticker price.
Some guys are going to say: yeah, but those cars are being abused on test drives, driven hard, etc.I would never buy one! LOL I always wonder ....how can you "abuse" the car if you don't know the car?! do they drive ~140mph? they drift it, etc.? I don't think so...
Btw. on '15 the warranty started the day I purchased the car. Not when the dealer started using the cars. I got this written in contract.