In 2000 I traded my Suburban (18 mpg actual) for this Civic.
I paid $4000 plus the 4000 trade for an actual price of $8,000.
I drove 77,000 miles as an "average" driver at about 33 mpg. Gas prices were about $2.50 average during that time, so I saved an estimated $4,180 there.
I've since hypermiled it for 39,000 miles, saving an estimated $4,325 vs 18 mpg at the same prices.
This car paid for itself before I hypermiled it. Since then it's paid for the trade in, so it's paid for the full sale price.