42 MPG Dodge Cummins Pickup

A fellow on the Diesel Truck Resource Forum said he heard of a 03 or 04 Dodge Cummins Pickup that got a certified 42 MPG. He said it was running on Biodiesel and probably had modifications. He thot it was either reported in a piece done on the History Channel, Modern Marvels: Car Tech of the Future or in a ecolonomics/drive to survive site. He's not sure. I've looked and can find nothing. Thot maybe someone on this forum might know something about this.

It`s sitting in my driveway right now! I wish. [;)] Like to know more.

Was it going downhill the whole time?

Mike Briggs: That was a very helpful response!!!

Mine gets about 22mpg. Not bad from a 3/4 ton 4X4 truck that weighs approximately the same as a battleship. With lightening, 2wd, some engine mods, etc., that doesn't sound too unreasonable.

There's only so much you can gain from modifications. Unless you're talking about completely changing the shape of the vehicle to reduce the drag coefficient (those trucks have horrible CDs - LOTS of drag, kills highway fuel efficiency), lightening it a LOT, etc.. 42 mpg for a big Dodge pickup with a HUGE engine is about as realistic as when people said their friend got 100 mpg on their cars in the 70s and 80s just by "modifying the carburetor". As engine size goes up, fuel efficiency goes down. As vehicle weight goes up, fuel efficiency goes down. As drag coefficient goes up, fuel efficiency goes down. Sure, you could probably make one of the diesel Dodge pickups get 42 mpg by bringing it down to a normal height (LOTS of drag in the wheel wells on jacked up trucks, as the Dodge's typically are), putting on smaller, low rolling resistance tires with smaller wheels (lower moment of inertia), covering the cargo bed (open beds make LOTS of drag), probably need to chop the roof down some to reduce frontal cross-section, doing lots of lightening, putting in a smaller diesel engine, and running it at about 30 mph constantly. But that's an entirely different ballgame from making a typical vehicle get 42 mpg in typical driving conditions. The engine mods would have to include either replacing with a smaller engine, or modifying for having some cylinders not used when not needed (a BIG modification). A huge V8 simply sucks fuel a lot more than a 4 cylinder.

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Originally posted by Mike Briggsly. But that's an entirely different ballgame from making a typical vehicle get 42 mpg in typical driving conditions. The engine mods would have to include either replacing with a smaller engine, or modifying for having some cylinders not used when not needed (a BIG modification). A huge V8 simply sucks fuel a lot more than a 4 cylinder.

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my dodge has a six-cyl. (and rarely breaks 18 mpg). keith

And to put things in perspective, a Benz 300D weighs about 4000 lbs. With a 120hp engine, it's rare to break 30mpg. The 45mpg is reasonable when you talk about a VW with a better Cd, lighter weight and even smaller engine. My father's '84 Jetta would get 60mpg cruising at 55mph.

i find it unlikely he gets 42mpg. maybe he's dyslexic? my 6cyl 95 ram gets up to 20 mpg. there is a performance chip that you can plug into the onboard computer. my mechanic says it can improve fuel efficiency up to 3mpg, but even with that and the realistic ones of the modifications mike briggs mentioned you still wouldn't break 25-26 mpg. must have had a tailwind, and been going downhill.

i think i figured out this little mystery. and the answer has nothing to do with stiff breezes, or long descents, but probably a slip of the ear. i've been running biodiesel blends for the past 2-3 months, and when i fill up at the station i've gotten in the habit of recording my mileage, consumption, yada yada yada. the last time i filled up my 95 dodge ram, to my delight, i came up with 30 mpg... or at least 30mpg of dinodiesel. this calculation didn't include the 10gallons of homebrew that i added last week. so to reconstruct a possible claim of 42mpg, it might have gone something like this: "i've been running b50 in my big truck now for quite some time, and am very happy with it. engine runs great, smells nice, and i get great fuel mileage. as a matter of fact for the last few tankfuls i've been averaging about 42 mpg of diesel fuel with the biodiesel helping me extend it even further." or something like that, you get the point. even though it is probably impossible to get that level of total fuel economy, he may be getting 42 miles for every gallon of diesel fuel he puts in his tank due to his 50% biodiesel "fuel additive".

ahhhh, that could be. Good thinking. [:D]

So if you fill your tank with B100 and one drop of dino diesel you could claim 1,000,000,000 mpg! [:o)]

I get infinite mpg most of the year. [;)]

I figured out our MPG of petroleum a few months back. The annual average for our four vehicles (F250-12MPG, 300TD-27MPG, B4`s-45MPG) comes up to around 400 MPG of petroleum. Now if I left the Ford and MB out and just figured in the two TDIs...... [:p]

Impressive!

The post on the Maui Biodiesel Forum @ http://biodiesel.infopop.cc/eve/ubb.x?a=tpc&s=447609751&f=415106403&m=607608044 is from Russ Gehrke. In the post he reports that Jerry McClain got 42 MPG. I know that the two of them are good folks and that Russ was getting in the high 20's while pulling a trailer down the interstate at 80 mph. But be aware that their rigs have had the exhaust systems changed, are mechanicaly modified, been rechipped, have propane injection and are computer controled for maximum efficiency. But they are still street legal machines that are driven all over the place. Russ also runs a biodiesel powered dragster and went 211mph (660 feet in 3 seconds). Jerry recently relocated from the St. Louis area to Tucson AZ where he opened shop. If you are in the area, you have a great resource to max out your truck. McClain Diesel Performance, 623-582-1239

WOW! I`m goong to have to see if those guys can retune our TDIs. How`s 90 MPG sound? [:p]

The obvious question that springs to mind it: how much propane are they using? If propane is always on, it seems to me that they could easily be making up half of the energy needed for driving with the propane and only metering the biodiesel tank. There was a post on here a while back about a "hydrogen" powerer Humvee that got something like 30mpg. But it turned out that the vehicle only injected a small amount of hydrogen into a diesel fuel engine, so while the vehicle couldn't run on straight H2, it did use some while dieseling, and was not accounted for in the mileage figure.

I just spoke to Jerry this afternoon. The 42 mpg truck was an 03 Dodge with the Cummins 5.9L common rail. Modifications included performance exhaust, propane injection, turbo mod, electronic controls and a wee bit of hydrogen injection. The rig still had a stock body, stock injectors and was (and still is) street legal. The 42 mpg was done on a track, so there was no "going downhill the whole time?". All the energy used, including the propane, was accounted for in calculating the 42 mpg rating. Jerry has sold that truck and the new owner gets between 800-1000 miles on the stock fuel tank (35 gal) along with the 8 gallon propane tank, that's between 23.5 and 29.4 mpg in normal (real world) street driving conditions. Currently Jerry is driving a 2004 1/2 Chevy Duramax with the LLY motor. He has of course tweeked it and is averaging 32 miles per gallon in general use. I was wrong in my first post. Jerry is located in the north Phoenix AZ area. The phone number was correct.

Over what distance was the 42 mpg test conducted? I can get 99+ mpg while coasting in gear on the highway...