Yes, it matters which state your car is registered in because each state has different regulations and requirements for registering and maintaining a vehicle. This can include differences in the required documentation, fees, and inspections, as well as insurance requirements. If you move to a new state, you will typically be required to register your car in the new state within a certain timeframe. This usually involves providing proof of ownership, proof of insurance, and paying any applicable fees. Some states may also require an emissions test or safety inspection before you can register your car. It's important to be aware of the specific requirements in the state where your car is registered, as failure to comply can result in penalties, fines, or even impounding of the vehicle. If you have any questions about registering a car in a particular state, you should contact the relevant state department of motor vehicles for more information.