Terrible to hear of your experience. Consumer to consumer transactions are always based on caveat emptor (buyer beware), so yes, a written receipt and some keynotes of the seller's commitments would have been the smart thing to do.
However, did you not exchange any text messages with the seller? Was the entire deal done face to face? You may be able to access your call logs if you are willing to take this further and register an FIR for misrepresentation.
Thank you for informing us. This car is still quite popular and at that price, I'm sure a lot of people might potentially be duped.
On a side note: How did the car drive?