Apparently a large swathe of RFID keys have been cracked. This makes it likely that the system that protects our car is crackable too. However, the requirement for proximity of the RFID device and the proper key in the ignition still leaves it difficult, given the U-channel key design (you can’t see the shape of the key without having it in your hand).
Link was rfidanalysis.org but flagged as malware.