You start My Summer Car with a sum of 3000 bucks. It should be enough for the first purchase of the necessary parts and it is, but in the beginning, you can get more than 4000 marks.
At home, go to the parents' bedroom (with a double bed). In the compartment, you will find a HOLIDAY PRESENT. Click F to open it, then F in an envelope labeled RANDOM GIFT MONEY. Your savings will increase by a random amount.