You can not take any legal actions against the seller because the car must have been handed to you as "AS IS NO WARRANTY". You could have taken some steps if the speedometer had been tampered or altered but I don't think so; it should have just been out of order.

Chill out, drive the car as long as it runs... last ghotnu parchha tyo missibisi lai, la nepal bata aayeka bhai bahini lai sikna ta sadhai kaam lagchha ni...