Is a car offer on OffLot binding right now?

No. OffLot is currently in preview, so nothing is binding and no dealer is notified when you make an offer. Listings, prices, dealers and lender programs are simulated, and real purchases, reservations, credit checks and deliveries aren't live yet. You can still try the full flow, including Make an offer, the status view in My OffLot and the pre-approval step, to see how it will work.