The 100 Mile-Per-Gallon Alternative Car

100 mpg with off-the-shelf technology? Jack McCornack isn’t crazy, he just believes cars can have a lot better fuel economy than we’ve settled for historically. Enter MAX — the MOTHER EARTH NEWS entry in the Auto X Prize competition, a $10 million race for 100 mile-per-gallon alternative cars. This article details MAX’s origins and the early stages of its development.

Learn about the 100 mile-per-gallon alternative car contest. Meet Jack McCornack, the brains behind MAX — the 100-mpg hopeful that you’ll be able to build.

Learn about the 100 mile-per-gallon alternative car contest. Meet Jack McCornack, the brains behind MAX — the 100-mpg hopeful that you’ll be able to build.

Photo by Jacky Leggitt

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Without any whiz-bang technology, we’re building a 100 mile-per-gallon alternative car for the Auto X Prize competition. MAX may not win the Auto X Prize, but it will prove a point that 100 mpg is within reach without futuristic technology.

The 100 Mile-Per-Gallon Alternative Car

There’s a contest underway to build 100-mile-per-gallon (mpg) cars that are practical and feasible for mass-production. Known as the Progressive Insurance Automotive X Prize, it will award $10 million to whomever can crack the 100-mpg puzzle and best demonstrate the achievement during cross-country races. When the races start in 2009, I’ll be behind the wheel of a sporty two-seater that will be as cool as it will be fuel-efficient.

Through a series of MOTHER EARTH NEWS articles and updates online, and at Kinetic Vehicles you can come along for the ride.

Who are You, and How did You Get This Awesome Gig?

I’m Jack McCornack, and I have a history of tinkering with “alternative” vehicles. I was an energy conserve-and-economize zealot before Jimmy Carter wore a cardigan. In the early ’70s, when we were only allowed to buy gas every other day, I drove past the long gas lines in a homemade contraption that got 125 mpg. In the late ’70s, while working with MOTHER EARTH NEWS, I made aircraft that got 40 mpg on home-brewed alcohol, and I helped with the tilting, three-wheeled 3VG concept vehicle. (You can read the original articles about these projects in The Flight of the Microlights and a two-part series Hey, Take a Look at Our Three-Wheeled Car and A Hybrid Vehicle Leaning Toward the Future: The 3VG (PART II).) These days, my latest company, Kinetic Vehicles, supplies parts (and sage advice) for lightweight do-it-yourself sports cars.

After a more than 30-year snooze, our country is waking up to the fact that treehuggers of yore were right — we’re running out of easy oil, if not all oil. So now the time is right for me to tinker anew and throw my hat into the Auto X Prize ring. The timing couldn’t be better: I’ve been building another cheapskate vehicle that just might fill the bill.

$10 million!! What is this X Prize thing?

The X Prize Foundation has an intriguing system of sparking technological breakthroughs: “revolution through competition.” The basic idea is to set lofty goals and give big money to the individuals or companies who best meet those goals. The contests are named after the people or companies who put up the prize money, which is how Progressive Insurance got in on the act for this X Prize. (For more on the Auto X Prize, see Racing to a Revolution.)

The 100-mpg goal of the Auto X Prize is appealing for many reasons. For one thing — stop me if you’ve heard this already — consumption of fossil fuels is damaging our environment. And I don’t know about you, but I seem to be spending a lot on gas these days. I know I could spend that money more wisely on something else.

So I’m gung-ho for the Auto X Prize, and I hope it stimulates the breakthroughs that 100 mpg will demand. But meanwhile I wonder . . . how close can I get to 100 mpg a breakthrough? What if I focus on here-and-now technology instead of later-and-wow solutions? What if I make a car that others could make for themselves? Last and most daring, what if I give it a tight budget and make the car pay for itself with the money it saves on gas? Enter MAX — MOTHER EARTH NEWS’ Automotive X Prize challenger.

Do you think you will win the X Prize?

I certainly doubt it. But just because I’m not expecting to win, doesn’t mean I’m not serious about the competition. My goal in doing this is to make a point. I’m seriously tired of Detroit telling us that a 35 mpg fleet average in 2020 is beyond its ability. I think we can get twice that with a car made from junkyard parts. I think any of the big automakers could win the Auto X Prize if they got serious about it. Seriously.

During the 12 years following the OPEC oil embargo of ’73, the average fuel economy of cars doubled. So don’t tell me the auto industry can’t step up to the plate.

However, following that, gas prices plummeted, the CAFE (corporate average fuel economy) standards leveled out in ’85 and our national mpg has actually declined since then. Automotive development has brought huge advances in many areas: amenities, emissions, horsepower and acceleration, but — when you look at the big picture — not in fuel economy.

Ah, the marvels of modern automotive engineering! We now get the same mileage in a high-performance 4,000 pound car as we used to get in a medium-performance 3,000 pound car and the same as our ancestors got in their low-performance 1,200 pound Model T. One can’t help but wonder, if the last 100 years of automotive engineering had been directed at improving efficiency, where would we be today?

Car companies do have one problem, but it’s a problem they brought on themselves: Economy cars aren’t sexy. The automakers have been encouraging us to buy bigger, fancier and more powerful cars for more than a century. Having convinced five generations of Americans that personal value and power are manifested by automotive value and power, it’s hard to sell us anything else. Even I have to confess: I’ve been a Mother Earth News reader most of my life, I embrace living wisely and I’m spearheading the MAX project . . . but yet, I don’t want an uncool car either. If you’re like me, though, we’re in luck because our car culture has left us loopholes.

A 100-mpg Car That's Also Cool? Are You Looney?

All else being equal, small cars use less fuel than big cars. But small cars aren’t cool . . . or are they? Thanks to the Corvette, the Viper and similar exotic sports cars from Europe — both modern and classic — sports cars are cool, even though they’re small. Thanks to our culture’s driving habits, two seats are plenty for the vast majority of our driving. Thanks to the limited engine power available 50 years ago, sports cars then had a minimum of frills, and sports racing cars were as streamlined as the rules allowed. And thanks to the power of nostalgia and the skyrocketing value of classic cars, there are few things cooler than a 50-year-old sports racer.

All of this comes together to form our styling target for MAX. It will look homemade enough for rat rod credibility, with a chassis and body that would have looked at home on the Sports Car Club of America grid at Laguna Seca Raceway, circa 1961. It shouldn’t have much aerodynamic drag and our weight goal is 1,250 pounds, so it won’t need much of an engine to pull it around. We’re hoping for tolerable performance with 30-some horsepower.

Yes, you read that right, tolerable performance. With about half the horsepower of a Geo Metro and about half the weight, MAX should accelerate about like a Metro, which is tolerable. There were plenty of sports cars in the ’50s that never had it so good. If you want high performance with your high efficiency, spend about $110,000 and get the all-electric Tesla Roadster. Now then, where were we?

What makes MAX go?

We’ve chosen an unconventional engine to give us that “tolerable performance,” a turbocharged 1100cc Kubota diesel. It’s an industrial engine, closely related to a small tractor engine. Kubota is a Japanese manufacturer of diesel power equipment. City folks may not be familiar with the company, but anybody with a farm knows who they are — more than one traditional farmer has a “mule” named Kubota.

The company does not make diesel engines for cars, but their engines are well-respected for agricultural equipment and electrical generators, and they meet the air-quality regulations for those industries.

We think we can meet the Auto X Prize exhaust emissions standards with this engine, but we really chose it for its extreme fuel-efficiency.

Could I really build one myself?

Here in Oregon, MAX is keeping me and my Kinetic Vehicles team pretty busy. As of this writing, we don’t have the final rules for the competition, so we’re not building the final chassis yet, but we’ve driven two Kubota-powered test cars and we’re learning fast.

Of course, to keep our economic edge, we’re going to have to keep certain trade secrets to ourselves and . . . BWAA-ha-ha-haa, just kidding. This will be an “open source” project: We’re going to share everything we do and learn with you and anybody else who wants to make a MAX of their own. Everything. Right down to the part numbers.

In the days when President Nixon set our speed limit to 55 mph and President Carter set our thermostats to 65 degrees, the homemade car of choice was a dune buggy. Folks tore the bodies off Volkswagen Beetles and installed fiberglass shells over the bare frames and engines. After a day of fun in the sun, making sand castles or whatever, you hosed it down like the beach toy that it was. This was the dawn of the “donor car,” a car you stripped for parts and then reassembled into the car you really wanted.

The Beetle was the ideal donor of the era — it was cheap and plentiful, and the kit car industry grew around it. Most kit cars were fancier than dune buggies — there was some differentiation between the interior and exterior, and many had “luxury” features such as roofs and doors — but they were all pretty Spartan. Then after the oil embargo and before the gas price drop, scads of cars from Datsun, Honda and Toyota arrived from the Far East, and suddenly, “Japanese car” wasn’t a punch line any more. They were light, reliable and economical. Now that they’re old and gray, they’re cheap.

I’d rather reuse than toss and replace, and it’s not just because I, too, am old, gray and cheap. A lot of energy goes into making automobiles, and energy conservation is the point of this exercise. Using old parts makes good sense, and getting as many parts as possible from one old car makes good sense. So we started scouting for an oil-crisis-era import to provide our axles, wheels and other running gear.

We found the perfect donor: a rusted-out Toyota station wagon, with a body so seasoned by a quarter-century of coastal living that one could reach into the car without opening doors or windows. Yet it was surprisingly sound in all other respects. It was immediately dubbed the “Corrode Warrior.” We cast and machined a Kubota-to-Toyota engine-to-transmission adapter, and my accomplices . . . assistants, I mean, assistants and I … high-fived each other and said “that’ll work” and “can’t imagine why it wouldn’t.”

Did MAX Actually Work?

While we wait for the X Prize Foundation to finalize the rules of the competition, we decided we’d use a Locost frame as our prototype. “A what?” you’re probably asking. It sounds kind of like Lotus and it is indeed inspired by the Lotus Seven sports car of the ’60s. But it’s low cost and simple to build (the Locost was originally designed as a high school shop project). So we wouldn’t be out a lot of money if it didn’t work.

Not that I was worried. We put the Toyota rear axle and front wheel assemblies in the Locost frame. They fit fine, as expected. We put in the brake and clutch master cylinders. Those took some chassis welding to fit but hey, no problem. You can’t make an omelet without welding a few eggs. The steering rack came from a Volkswagen, that took a bit of head scratching. We also had to make a few modifications to the Kubota for ground clearance and plumbing, which was easy once we figured it out. Drafting by night and fabricating by day, I’d pound away on my computer till the wee hours and weld together what I’d drawn when the sun arose.

Throughout the process, people have asked, “Are you sure that a tractor engine can drive a car?”

“I can’t imagine why it wouldn’t,” I say.

Then they say, “I guess we’ll know when you’re done building it.”

At first I thought that would be soon enough for me. But then I chickened out. I didn’t want to build an entire car before discovering I had a defective imagination, so we stuck the Kubota in the Corrode Warrior and went for a test drive. It was fun. It went up to 67 mph before the governor kicked in (we may want to do something about that) and though it was more of a tortoise than a hare, it wasn’t the slowest car I’ve ever owned.

Because I couldn’t drive it to town without everyone asking the obvious question (“What kind of mileage do you get with that?”), I put together an instrument package — a GPS device, an oven timer and a 12-ounce honey bear bottle for a fuel tank. I did four mileage runs, averaging just more than 37 mpg. Not bad for a station wagon!

We could have made improvements and maybe reached 40 mpg, but it was time to retire the Corrode Warrior before a police officer decided the tractor exhaust might obstruct the driver’s vision. We stripped out the good parts and sent the body to the crusher — ashes to ashes, and rust to rust.

What's Next for MAX?

The good parts went back in the Locost, and on June 2, MAX ventured to the Department of Motor Vehicles, where it was deemed street legal. We haven’t a hint of mpg data yet, except it only has a 1 gallon tank and we haven’t had to add any fuel for a couple of weeks.

Now that MAX is running, people have stopped asking me if it’s going to work. Now the common question is, “How well is it going to work?”

We’ll have some answers soon. After MAX is reasonably safe (it needs a roll bar, for one thing) and reasonably comfortable (real seats instead of lawn furniture), we’ll see what small and light will do for gas mileage, and set our baseline. Then we’ll start streamlining and testing. We may have to make big changes when the final rules come out. The X Prize timeline calls for qualifying races in the spring of 2009, with the final competition in the fall. MAX is going to work, we just don’t know if it’s going to be with fantastic mileage or merely great mileage. 

But one way or another, MAX will be a contender. If we can build MAX with half the drag of the Corrode Warrior, we’ll have a 75 mpg sports car with an engine that will last for 500,000 miles. And then, well, we’ll have to start thinking seriously about how to get to 100 mpg. Stay tuned.

You can keep up with MAX’s evolution through our Green Transportation blog by searching on MAX updates, and at Kinetic Vehicles.

4/23/2014 5:15:14 PM

Hello, I have been looking for HHO kit. I found one of the kits below, but not sure it is worthwhile to purchase. Can you please recommend good HHO kit, which you tried? My target is 20% MPG increase with reasonable ROI. Thank you in advance!

john teague_2
2/13/2009 10:36:48 AM

how much does or will it coast now?

tim flinn
2/11/2009 9:34:11 AM

The Locust (low cost) was based on the Lotus 7 (now the Caterham) that, depending on engine used, can hit 150mph)and can out accelerate every Italian super car. The orginal Lotus 7 was a kit car. The Locust like the Lotus orginated in Britain in the last ice age. The French sell the Maxem (Maxham?) which is based upon motor cycle parts, uses the Kubota diesel and does 90mpg (or so a proud owner claimed to me) but top speed is not sixty. It is a weather proof four seater (for 4 tiny Frenchfolk). It is road legal in Europe, but I wouldn't want to crash into anything larger than an empty matchbox. Look it up on the web.

clinton crawley
10/18/2008 11:25:14 PM

Gary Brown in Georgia has been putting tractor engines in trucks and cars. He's getting about 50 mpg in trucks and about 60 in some cars. His website is I personally feel that HHO gas(hydrogen or Brown's gas)made from plain or salt water is the only way to go. Three fourths of the earth's surface is water--you can't find anything more abundant that that.

jack mccornack
8/11/2008 3:05:25 PM

:-) It takes more power to generate hydrogen than is released by burning hydrogen, but many people tell me it works for them. I've yet to hear a convincing explanation of how it's supposed to work, but there are lots of discussion groups on the internet and you may learn something I haven't.

geetz romo
8/11/2008 12:49:42 PM

tack on a hydrogen (HHO) booster and see how much better mileage and lower emissions you get. You should get better torque as well.

john rockhold
8/7/2008 3:33:26 PM

(forwarded from Jack McCornack) When Colin Chapman designed the Lotus Seven, he called it a "four wheeled motorcycle," and from a passenger safety standpoint, that's pretty close. Is it "street legal"? Could an auto company do this? Sure it could--Caterham Cars got the rights from Lotus years ago and you can buy a brand new Caterham Seven today. But we can and should do better. You're seeing MAX at the beginning of its development, and the Auto X Prize rules demand we get our car to current safety standards before the driving competition begins. We're working on side intrusion, and we're already pretty good on front and rear intrusion (and sadly, I can prove it--see my blog for details). Ditto for emissions, we already meet the latest standards for agricultural equipment and we think with a year's work we can meet auto standards too. So stay tuned, and feel free to prod us if it looks like we're not making fast enough progress.

john rockhold
8/7/2008 1:19:50 PM

(forwarded from Jack McCornack) Hi George, tell us more! I know that chassis-wise (and currently body-wise), this car's inspiration dates back half a century, however, it has other features to bring it up to current needs. I think folks should have been building these in 1981 but once the first wave of the fuel crisis ended, interest in fuel efficiency kinda dried up. Anyway, it would be good to be reminded who was keeping the faith back then, and I sure don't claim to be the first to think small-car-small-engine is a good way to go.

robert petrach jr.
8/7/2008 5:54:50 AM

This article is a tremendous disservice to the readers. This is a death trap. The frame is touching the occupant, no crush zone, no room for intrusion. The engine would not come close to passing emissions. Max is right in pointing out weight as an important factor and his choice to turbo charge probably gained him 10-15 % efficiency. But to say this is "street legal" and implying an auto company could do this is just sad. The comment about auto companies not being able to meet 35 mpg "FLEET AVERAGE" would imply that the auto companies can or should control what people buy. The auto companies will reach that 35 mpg goal and more as gasoline prices rise. The marketplace will decide. If we see $15 a gallon gasoline consistently for the next few years, I'd predict that 35 mpg will be achieved in the 2010 model year. People just won't buy vehicles that get less. You won't have one person driving 80 mph down the interstate in an 8 passenger 15 mpg Suburban anymore. But the fact is many cars have been available for a long time that got better than 15 mpg, the customer just chose not to buy, instead chose to buy a 5000 lb / 400 horsepower sedan that would blow the doors off a 70's "muscle car" or a 4 door 4 X 4 pickup for the daily commute on paved roads.

8/1/2008 3:52:45 PM

This car was already built in 1981 nothing new this is just a copy