Plug-and-Charge (PnC) standards such as ISO 15118 enable Electric Vehicle (EV) authentication against Charge Points (CPs) without driver intervention. Credentials are stored in the vehicle itself making methods using RFID cards obsolete. However, credentials are generated in service provider backend systems and provisioned via the Internet and not in a secure Hardware Security Module (HSM) within the vehicle. In this paper, we propose HIP, a backwards compatible protocol extension for ISO 15118 where keys are generated and stored in a Trusted Platform Module (TPM) within the vehicle. Our implementation and evaluation show that our solution is feasible and is a viable option for future editions of ISO 15118.