2003 Honda Civic CNG MPG & Specs — Real-World vs EPA, All Trims

Is the 2003 Honda Civic CNG good on gas?

Real-world MPG vs the EPA number

The EPA figures above come from a standardized dynamometer test, not the open road — real-world MPG typically runs a bit lower depending on your driving, climate and terrain. That's true of every car on this site, old or new.

This 2003 model was originally EPA-tested under the pre-2008 2-cycle method, which didn't account for highway speeds over 60 mph, air-conditioner use, or cold starts. When EPA overhauled the test for model year 2008, city ratings fell by about 12% and highway by about 8% on average industry-wide — and EPA retroactively adjusted every 1984-2007 rating to the stricter standard so old and new cars could be compared fairly. The MPG above is already on that modern scale — the window sticker on this car when it was new likely showed a higher, pre-2008-method number.

For its most efficient trim, the EPA estimates about $1,600 a year in fuel (15,000 miles) — roughly $133 a month.

2003 Honda Civic CNG trims & fuel economy

2003 Honda Civic CNG specs

What the EPA test-car listings record for this model year — every combination sold is a row in the trims table above.

Other years of the Honda Civic CNG

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1 trim(s) · EPA FuelEconomy.gov data retrieved 2026-07-24 · fuel prices AAA national average as of 2026-07-05.