Could the buyer decline purchase order after signing to buy a car less then 24 hours when car never left dealership lot never sign bill of sale and have not financial aprove?

Yes, the buyer can likely decline the purchase order within 24 hours if they haven't signed a bill of sale or received financial approval. Since the car never left the dealership lot, and assuming there are no binding agreements in place, the dealership may allow the buyer to back out. However, the specific terms and conditions of the purchase order and local laws may also play a role, so it's advisable for the buyer to check with the dealership and possibly seek legal advice.