It would be a CVT.
But, the choice isn't clear yet.
I think it would be a Sentra or a Focus first. Maybe a bigger or hybrid car next.
I know a Sentra 2009 did 33.6 MPG (7 liters per 100 km) on a road who have alot of hills and big turns.
CanadianDriver Comparison tests and reviews Special Feature: 2008 CanadianDriver 50-litre Challenge
According to this link, the focus and sentra did 35.11 MPG and 33.6 MPG respectively on highways.
I guess I'll have to test them out.