If you have a gasoline car registered after January 2000 (EURO 3 standard) or a diesel car registered after January 2006 (EURO 4 or 5 standard), you can drive to your hotel if it has its own parking space associated with the Madrid Central system. You may only park in the hotel parking space. Otherwise, if your hotel has reserved space for guests to get on and off vehicles, you will have to register your car in order to get through.
If your car has an ECO label or is a Zero Emissions vehicle, you can drive around Madrid Central and also park in the regulated parking spaces (SER) for two hours if you drive ECO label cars (other cars have no time limit).
If your car does not belong to these categories, forget about driving in the city center and enjoy Madrid penalty-free.