This one is easy IMO. Jesus would drive a shuttle van similar to this one:

http://www.tescobus.com/bus/goshen_pacer.html

(Side note - I wonder if the disciples would have shouted "SHOTGUN!" as they headed to the vehicle???)

Regarding fuel economy, he wouldn't be too worried. If the man turned water into wine and could feed a crowd with only a loaf of bread and a few fish, then filling the fuel tank of whatever he drove would not be a major problem for him!