The U. S. Government fuel economy comparisons (subject of previous threads) is a good way to compare costs and fuel use. Most vehicles are included in the tables.

Using Chevrolet 2009 as an example:
Malibu 2.4l 4cyl auto- City 22, Hwy 33, cost $1409/15000 mi.
Malibu 3.5l 6cyl auto- City 18, Hwy 29, cost $1665/15000 mi.
Malibu hybrid 2.4l 4cyl auto- City 26, Hwy 34, cost $1263/15000 mi.

A mid-size SUV- Jeep
Cherokee 3.7l 6cyl auto 4wd- City 15, Hwy 20, cost $2152/15000 mi.
Patriot 2.4l 4cyl auto 4wd- City 20, Hwy 22, cost $1742/15000 mi.
'Clunker'
(1985 Jeep Comanche, 2.86l 6cyl auto- City 15, Hwy 17, cost $2288/15000 mi.)

US Fuel economy