Getting chased by someone who's out to kill you. Considering they are hired, and because of that are prepared with a good chase car, I want something that has some kick to it and will blend in. Possibly an 94-96 Impala SS, or an LSx powered car, 6 speed. A stock one would be the most likely, and a slightly modified one, under the hood, if available would be the most desirable to get away.
Disaster? I think nuclear, don't think it's been mentioned. You'll need something rugged, able to carry at minimum three other passengers, and will have no computers whatsoever to be safe from EMP. Toyota Land Cruiser-Proven. If it can win in Dakar and Botswana stock, I think it could drive me to safety, over obstacles, carrying everything I'd need for a short time and with people.