Cracked software often has features disabled, is unstable, or is the "Demo" version mislabeled as a full version. A user on the Simsonforum.de confirmed that the demo "kannst auch nicht speichern und nix" (you can't save or do anything) and that the "Demo ist aber komplett anders als die voll Version" (the demo is completely different from the full version).
If you cannot afford the game, consider watching detailed playthroughs on YouTube or using the free demo. No simulation is worth the risk of downloading cracked software from Mega. simson tuning werkstatt 3d serial key mega