That's interesting too. The Loremo (see other article) has got a bit more space and will require about 1 gallon per 120 miles.

This is really just tinkering around with an engine design which is over a century old. It has been known for decades that if you take all the weight out of the vehicle you can get far greater miles per gallon (see the bubble cars of the 1960s). Internal combustion engines are extremely inefficient and waste a lot of energy as heat. I would be in favour of moving to new engine designs which do not run on hydrocarbons, are radically simpler in their operation and having zero emissions such as this one http://www.engineair.com.au