If you're thinking about upgrading your BMW after purchase, there are a few things you should keep in mind. First, while it is possible to upgrade certain aspects of your BMW, not everything can be changed. For example, the engine size is set at the time of manufacture and cannot be altered. Second, any modifications you make will likely affect your warranty coverage. Be sure to check with your dealership or service center before making any changes to ensure that your warranty remains valid. Finally, keep in mind that some upgrades may actually decrease the value of your car when it comes time to sell. So if you're planning on upgrading your BMW, be sure to do your research first!