Honda Civic HX Gas Mileage Project

If you’re looking for an inexpensive used car that gets great mileage, it’s tough to beat the Honda Civic. They’re affordable, plentiful, and reliable – as long as you keep up on basic maintenance.

Over the years, the VX, HX, and HF models have been the most fuel-efficient conventionally-powered Civics. As wild as it may sound, the tiny 1984 Civic CRX HF was officially rated at an astounding 67 miles per gallon highway. Now some folks might not believe this today, but there are tests to prove it.

The United States Auto Club (USAC) drove a fleet of four 1984 CRX HFs cross-country, back in the day, and achieved a remarkable 71.6 MPG average for the entire fleet.

On one leg of the USAC’s testing – westbound from Flagstaff, Arizona to Las Vegas, Nevada – one of the cars averaged an eye-popping 86.3 MPG, with the aid of a tailwind and a largely downhill run.

If you go to the US government fuel economy website today, you’ll see the 1984 CRX HF is now listed at a relatively paltry 47 MPG … a whopping 20 MPG drop from their original rating.

What’s up with that?

Editor’s Note: Our Civic Gas Mileage Ratings Page lists the original sticker MPG numbers, not the revised EPA numbers.

Revisionist statistics aside, I’d absolutely love to have the chance to test and tweak a CRX HF to see how it would fare on the road today, given our higher speed limits and E10 gasoline.

Unfortunately, unmolested CRX HFs are very hard to find these days. Tuners love the HF because it is extremely light. They rip out the original tiny 1.3-liter engines and swap in larger and more powerful VTEC units from newer Hondas and Acuras, often imported directly from Japan.

It seems like every time I find a clean original CRX HF, it’s either on the other side of the country or I’m broke.

Often it’s both.

While clean CRX HFs may be scarce, there are plenty of Civic HX coupes out there (or CoooPAYs, as they say on the other side of the pond). These newer Civics offer a bunch of advantages … starting with a back seat.

The manual HX coupes were originally rated in the low-to-mid forty mile per gallon range on the highway. Not a bad place to start. Real world reports show those numbers to be achievable.

2000 Honda Civic HX Coupe

So we’re currently looking for a manual-equipped 1998 or newer Civic HX for our first MPG project car.

Why 1998? On-board Diagnostic (or OBD) ports can be found in all cars that are 1996 or newer. We need OBD in order to fit the Civic with advanced instrumentation and fifteen years is a good spread.

Lets get down to it … What’s this Civic Gas Mileage Project all about?

In short, we want to see if it’s possible to push a Civic HX into the 50 mile per gallon highway range with some straightforward tweaks. That means no snake oil, fart can mufflers, or dangerous highway driving techniques, like drafting.

With luck, we’ll get this project done over the summer. But we’ll need your help.

Our goal is to produce a cool little documentary series covering the process of improving the Civic’s real world fuel economy, along with its handling and in-cabin amenities.

This project will have some unique twists, no doubt about it … and we’re likely to encounter the inevitable bumps in the road.

While we’re planning a show around it, this won’t be a show car … it’ll be a driver, through and through.

So stick with us, and stay tuned. We’ll be sharing more details in the coming weeks…

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8 thoughts on “Honda Civic HX Gas Mileage Project”

  1. I once owned a 96′ Civic HX with a 5 speed manual. It was the first car I purchased new! I never recorded less than 34 MPG in any type of driving. The best highway mileage I achieved was 46 MPG. I owned it for 5 years and put 145k miles on it. The only issue I had was a broken ground terminal which I repaired myself for a couple of dollars. Also changed the timing belt and water pump at 100K which was easy. Sold it to a friend and it’s still going strong with over 260k on it!

  2. 260K! Great to hear, Mike! I’ve found a few Civic HXs locally. The trick is finding a clean one that hasn’t been fiddled with … it needs to be as close to stock as possible.

  3. Just picked up an unmolested 1998 Honda Civic HX 5mt. Has 130,xxxmi on it. Runs like a champ. Currently getting around 37mpg. Would like to get a little more but my part of Florida is not as flat as most people think.


  4. It is possible to get 50+mpg, it has been achieved with another alternative to the hx’s d16y5. The gentleman used a 3 stage vtec d15b and added a turbo setup. Not only did he make good power but he was also able to utilize the dual vtec solenoids on that particular motor. It may be the only route I’ll be taking with my same setup.

  5. I have a 1998 civic HX. I just turned 509,000 on it. My last fill up I got 39 mpg. In the summer I average between 40-42 mpg combined. Its been a great car. When the time comes or if it comes, can I buy a new engine for it.

  6. Wow, Kim … 509K? That’s awesome! You should be able to find a remanufactured engine for it, down the road. The trick is to get the exact engine …

  7. I just bought a used 96 civic hx from a kid whom I’ve discovered doesn’t know much about working on cars. He installed an aftermarket high flow intake and “coffee can” muffler.. And I’m wondering if they might be the reason I’m only getting 31-35 mpg?? I’m thinking of replacing the muffler anyway because the noise while traveling distance drives me nuts! Would the stock factory muffler be the best option or would a separate type of performance muffler be better?

  8. @Daniel – I love a good exhaust note, but coffee (a.k.a.: f*rt) can mufflers are hideous. That would be the first thing I’d replace, whether or not it had any effect on MPGs. 🙂 I would use a quality aftermarket exhaust system, rather than the factory stuff, as the OEM Honda parts are likely to be a good bit more expensive. The trick is to find an affordable system with an acceptable sound.

    Check the oxygen sensors. They’re a likely culprit for poor mileage.

    Do you have the original intake?

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