Since it is business, nothing couldn't be discussed. However, you should have the idea if it is repairable or not. You may not be happy to get a repaired vehicle but with many potential problem.
You can bargain them with this request to put more presure on them. At the same time, you can negotiate with them for more compensasion for upgrades, recent parts change etc.
If you have any health issue due to the accident, even it is minor, find a lawyer for claim. The insurance company usually pays more if you have a lawyer.