2006 Honda civic LX Auto very economical.
 

My mom bought a 06 civic lx not too long ago. I made a thread about it. Anyway she has been constantly getting high 20's. So I plugged up the SG2 to her car, calibrated it to her engine and we went for a drive.

On the streets she got 41.7mpg
On the freeway 64mph@65MPG

As long as the car is going 37mph or higher it's very efficient. So we used moderate pedal pressure to get to 37mph and then cruised at about 39-40mph. Coasting before lights was used.

I managed to pull of a 40.5mpg on the street.

This is not the hybrid civic, just a regular LX:D

the r18 never fails to impress, with the right hands 80 mpg should be possible on ideal conditions.

The R18 is a good engine with relatively tall gearing in the 5th, I could se getting 50 in it daily for my old commute.