Gasoline vehicle efficiency 1500 miles per gallon

David French writes:

Electric vehicles are going to have to compete against continued improvements in gasoline vehicles. Furthermore, even if there's a gasoline shortage, vehicles can run on natural gas.

Here's a link to a University of Ottawa team who have designed a car capable of travelling 1,500 miles per gallon:

The good news is that their advanced motor design can be used in a gasoline electric hybrid.

My question is: how are such high efficiencies achieved?

David J. French