Here's an interesting titbit, most tsunamis travel at hundreds of kilometres an hour while still propagating through the open ocean. Once they start to stack up and form the wall of water commonly associated with tsunamis, yes they do slow down, but it's still nearly impossible to outrun a tsunami. The smart thing to do would be to get somewhere stable and high, not into a car 🙂
But assuming I had 5 minutes to run from a theoretical something and escape with my life.. hmm, hard one. I guess I'd pull out my hard drives, my camera, laptop, and my important documents (passports, birth certificate, other certificates, etc)