I hope this information is still relevant. Since you're going to drive, I highly recommend that you bring a passport with you. It's always best if you can prove to customs your citizenship, otherwise it would be a big hassle. If you're lucky and the agent is nice, you can get by with a driver's license. If not, you'll be sent to the immigration office for processing which could last a while. From personal experience, it has happened a few times; quite a hassle but it's not surprising as some of the agents "profile."