Mod the Sims 2 has released some special collections on their forums which enable you to buy weather, cars and reward objects. By downloading and installing these files into your Collections folder, mentioned features will be made available by buying the necessary objects through the collections. They're still in beta stage and might crash your game, so you should read the included warnings and back-up any data before using these collections, especially the weather. You can find the collections in the Downloads section and the forums (specifically the Beta Testers and General Modding forums).