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Pump Pain - Jeep Fuel Numbers

1978 Jeep Cherokee Chief
Christian Hazel
| Brand Manager, Four Wheeler
Posted April 1, 2013
Photographers: JP Staff

Damn the mpg!

Getting upset every week when you fill your Jeep with $3-to-$4-per-gallon fuel? With oil companies getting rich off us and a president reluctant to push any legislation to lower fuel prices, it seems there’s no relief in sight. But before you add a 30 mpg vehicle to your Jeep fleet for commuting or worse, turn your back on Jeeps altogether, ask yourself this question. How bad is your Jeep when you consider all the factors?

Look at it this way. According to the U.S. Department of Transportation, the average American drives 13,476 miles a year. For simple math, we’ll call it 15,000 miles. If your Jeep gets 15 mpg sucking $3.50/gallon fuel, your annual fuel bill is $3,500. On average, a used, reliable 30 mpg-capable sedan will run you $10,000. That’s being generous and assuming you don’t wanna step into a claptrap junker or micro-size Euro-speedo-funboy-neuterwagon. At 30 mpg, your annual fuel bill is now $1,750. Congratulations! You’ll have to drive your Euro-speedo-funboy-neuterwagon more than 5.7 years before you actually see any return on your investment. That’s almost 6 years of not being able to see the scenery on the other side of the guard rail, living in fear of getting hit by anything heavier than a gerbil, and not having the joy and sense of pride that comes from driving a Jeep. And after 5.7 years your econo car will most likely be ready for a replacement.

Just for giggles, we stacked a couple of the staffer’s real-world project rigs (and a couple of Jeep’s press fleet vehicles) up against the $10,000 Euro-speedo-funboy-neuterwagon to see after how many years it would take to actually start saving money on fuel. Surprised?

Vehicle: 1978 Cherokee Chief
Engine/Mods: AMC 360 V-8; Edelbrock 650 cfm four-barrel; MSD distributor with hot advance curve; Edelbrock Performer manifold; Dynomax muffler
Transmission: TH400
T-Case: BW1339 Quadra-Trac; part-time kit
Axles: Dana 44 (front and rear), 3.54s
Final Drive Ratio: 3.54:1
Tires/Wheels: 33x12.50R15 Mickey Thompson Baja Claw TTC on 15x8 Mickey Thompson aluminum Sidebiter
Overview: The engine is old and tired and (before the head gasket blew) had low compression on Number 6 and 8 cylinders. Besides the Dynomax muffler, the exhaust is stock. Yet the AMC has enough grunt to get the barge moving with the 33s around town, and it normally cruises around 2,800 rpm at freeway speeds with no issues.
MPG Notes: Combined average of 13.7 mpg, with highs of 15.5 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 4.8 years

Vehicle: 1989 Wrangler
Engine/Mods: Factory 2.5L TBI four-cylinder; home-built cold air intake
Transmission: Swapped-in AX15
T-Case: NP231
Axles: Dana 30 (front); Dana 35 (rear), 4.88s
Final Drive Ratio: 3.86:1
Tires/Wheels: 31x10.50R15 Toyo Open Country AT II on 15x8 Black Mountain steel
Overview: The engine has about 200,000 miles and runs pretty rich ’cause the emissions devices are currently removed, but otherwise it’s dead reliable and buzzes down the road just fine.
MPG Notes: Combined average of 17.55 mpg, with highs of 19.3 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 8.1 years

Vehicle: 1978 J-10
Engine/Mods: AMC 360 V-8; Motorcraft 2150 carb; 14-inch open element air filter.
Transmission: T-18
T-Case: Dana 20
Axles: Dana 44 (front and rear), 4.10s
Final Drive Ratio: 4.10:1
Tires/Wheels: 9.00-16LT STA Superlug bias-ply on 15x8 Wheel Vintiques steel
Overview: Aside from the lift and tires, the truck is basically stock with about 91,000 miles on original engine. The engine buzzes at freeway speed and smells of burning oil pretty bad, but then again so do we.
MPG Notes: Combined average of 8.7 mpg, with highs of 12 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 2.3 years

Vehicle: 2012 Wrangler Unlimited Sport
Engine/Mods: Dead-stock 3.6L Pentastar V-6
Transmission: A580 five-speed automatic
T-Case: NV241
Axles: Dana 30 (front); Dana 44 (rear), 3.21s
Final Drive Ratio: 2.66:1
Tires/Wheels: 255/75R17 Goodyear Wrangler SR-A on factory 17x7.5 aluminum
Overview: We borrowed a hard-top Unlimited Sport for a couple weeks and were amazed despite the tallish tires and 3.21 gears how quick and nimble it was around town and how miserly it was on the fuel.
MPG Notes: Combined average of 18.7 mpg, with highs of 24.5 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 9.5 years

Vehicle: 2013 Compass; 2013 Patriot
Engine/Mods: Dead-stock 2.4L four-cylinder
Transmission: CVT automatic
T-Case: Yes
Axles: IFS/IRS, 4.12s
Final Drive Ratio: N/A
Tires/Wheels: 215/60R17 all-season touring tires on factory 17x6.5 aluminum
Overview: We drove both Patriot and Compass Latitude 4x4 models for several weeks with virtually no performance difference between the two. The 172hp 2.4L revs willingly but the CVT transmission makes driving it a disappointment. Unless we were on the freeway for long, flat stretches, we generally got better mileage with the 3.6L Pentastar Wrangler Sport.
MPG Notes: Combined average of 18.5 mpg, with highs of 24.0 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 9.2 years

Vehicle: 1998 Cherokee
Engine/Mods: 4.0L HO; factory MPI with Edge 62mm throttle body and tuner; Banks Header; AEM Brute Force air intake; Gibson muffler and 21⁄2-inch tailpipe; DUI firepower kit with 18V step-up upgrade
Transmission: AW4
T-Case: NP242
Axles: Dana 30 (front); Dana 44 (rear), 4.56s
Final Drive Ratio: 3.42:1
Tires/Wheels: 33x12.50R15 Goodyear Duratrac on 15x8 MB Wheel Model 72
Overview: The engine and transmission have 260,000 hard miles on them but both are still in relatively good shape. Mileage varies greatly on the highway. If we go with the flow of traffic it drops off but if we stay at 55-60 mph it increases.
MPG Notes: Combined average of 15.8 mpg, with highs of 16.5 mpg at freeway speed or up to 19.8 mpg at 55-60 mph.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 6.4 years

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