For the old man, retiring is something that he wanted for a long time, so he can go back to the mountains, where he grew up. However, he knows that won't be easy since the path ahead is not only long, but full of danger. Now, that he is old, he wants to get back there and spend the rest of his days.
The idea of the game is to drive your car to the mountain. You can't do that in jut one try. Just drive your car till there are no fuel. You need to pick up the coins on the road and you can use those money to buy upgrades for your car.