A car was part of a competition sponsored by Shell in the 70’s and then sat in seclusion/obscurity and has since been rediscovered. The article states that it uses a chain drive system to save on weight, the cabin is stripped of everything except the very essentials and that it heats the fuel into vapor and insulates the fuel delivery system. It is said to have acheived 376.59 mpg at a steady 30 mph on a track.
See: Hybrids, meet your rival — it gets 376.59 mpg (Seattle Post-Intelligencer)
Here’s to some hope for more efficient autos.