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Pump Pain - Jeep Fuel Numbers

Posted in How To on April 1, 2013 Comment (0)
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Pump Pain - Jeep Fuel Numbers
Photographers: JP Staff

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

Vehicle: 1967 M-715
Engine/Mods: 366ci big-block Chevy V-8, 650 cfm Holley Truck Avenger; S&B air filter; MSD HEI distributor; long-tube fenderwell headers; dual 2½-inch 40-Series Flowmasters
Transmission: Spicer 3053A
T-Case: Divorced NP205
Axles: Dana 60 (front); Dana 70HD (rear), 4.56s
Final Drive Ratio: 3.88:1
Tires/Wheels: 37x12.50R16.5 Goodyear Wrangler MT OZ on 16.5x8 two-piece HMMWV 12-bolt wheels
Overview: The engine is tired and old and is putting out only 150hp/250 lb-ft as tested on a dyno. Still, it cruises on the highway nicely at about 2,800 rpm at 70-75 mph.
MPG Notes: Combined average of 6.1 mpg, with highs of 6.3 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 1.5 years

Vehicle: 1991 Comanche
Engine/Mods: 4.7L inline-six stroker; factory MPI with 68mm throttle body and 24 lb-hr injectors; APN header; full 21⁄2-inch mandrel-bent Dynomax exhaust including 21⁄2-inch catalytic converter; mechanical fan delete; 99-up manifold; DUI firepower ignition
Transmission: AX15
T-Case: NP231
Axles: Dana 44 (front and rear), 4.56s
Final Drive Ratio: 3.60:1
Tires/Wheels: 35x12.50R17 Dick Cepek FC II on TrailReady HD17 aluminum beadlock (not shown in photo)
Overview: The engine is still fresh and with a ton of torque down low this truck is a blast to drive. Between spirited driving and frequent trips to the dyno, there aren’t too many tanks of gas that have solid mileage numbers.
MPG Notes: Combined average of 13.0 mpg, with highs of 16.5 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 4.4 years

Vehicle: 2001 Wrangler
Engine/Mods: 4.0L HO; factory MPI system with 62mm throttle body; Borla Header; 21⁄2-inch Flowmaster Hushpower muffler; AEM Brute Force intake
Transmission: NV3550
T-Case: NP231
Axles: Dana 30 (front); 9-inch (rear), 4.56s
Final Drive Ratio: 3.56:1
Tires/Wheels: 315/75R16 Goodyear MT/R with Kevlar on 16x8 Ballistic Off Road Outlaw
Overview: With 150,000 miles on the engine and a freshly rebuilt transmission, our Wrangler runs very well and still puts down a lot of power for a relatively stock 4.0L. Its numbers of 155hp/200 lb-ft is pretty common. But it is a soft top Jeep that is often driven without the top or doors, and that affects mileage.
MPG Notes: Combined average of 12.0 mpg, with highs of 15.0 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 3.8 years

Vehicle: 1956 CJ-5
Engine/Mods: ’98 2.5L MPI four-cylinder; Airaid intake; Maganaflow catalytic converter and muffler; custom 2¼-inch exhaust; new O2 sensors.
Transmission: AX5
T-Case: NP231J
Axles: Dana 30 (front); Chrysler 8.25 (rear), 4.10s
Final Drive Ratio: 3.49:1
Tires/Wheels: 33x10.50R15 BFG KM2 on 15x7 Wheel Vintiques steel
Overview: Despite pushing an all-steel ’56 CJ-5 body full of camping gear atop a custom heavy-duty frame, our CJ delivered respectable mileage, although it could use some lower axle gears on the highway and off-road.
MPG Notes: Combined average of 15.0 mpg, with highs of 20.0 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 5.7 years

Vehicle: 2001 Grand Cherokee
Engine/Mods: 4.7L V-8; Airaid intake and throttle body spacer; Superchips TrailDash; muffler deleted.
Transmission: 545RFE five-speed auto
T-Case: NP242
Axles: Dana 30 (front); Dana 44A (rear), 3.73s
Final Drive Ratio: 2.49:1
Tires/Wheels: 295/70R17 Nitto Terra Grappler AT on Summit Racing 17x9 Legend 5 Series Gunmetal Wheels
Overview: Between the rumbling exhaust, whine of the Airaid throttle body spacer, and new shift points with the Superchips TrailDash we have a hard time not driving this thing with a lead foot. Occasional towing, traveling with a canoe on top, and go-fast desert driving all lower the fuel economy. The Jeep could use some slightly lower axle gears, maybe 4.56s or 4:10s.
MPG Notes: Combined average of 13.0 mpg with highs of 15.0 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 4.4 years

Vehicle: 1997 Wrangler
Engine/Mods: 2.5L MPI four-cylinder; 4.0L throttle body
Transmission: AX5
T-Case: NP231J
Axles: Dana 30 (front); Toyota 2WD Tacoma 8-inch (rear), 4.88s
Final Drive Ratio: 4.15:1
Tires/Wheels: 33x12.50R15 Pro Comp Xtreme MT on 15x8 Pro Comp Series 7069
Overview: This Jeep sees time as a parts runner and gets driven hard on the trail. It is pretty lightweight at about 3500 lbs with driver and always has a Soft top and occasionally soft doors on long trips.
MPG Notes: Combined average of 13.0 mpg with highs of 15.5 mpg on long freeway trips.
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 4.4 years

Vehicle: 2007 Wrangler
Engine/ Mods: 3.8L V-6; AFE intake, Scorcher tuner, and after-cat exhaust; Rusty’s headers; Performance Distributors Firepower 3.8L
Transmission: NSG370
T-Case: NV241OR
Axles: Dana 44 (front and rear), 4.10s
Final Drive Ratio: 3.44:1
Tires/Wheels: 305/70R17 Goodyear MT/R on 17x8.5 AEV Pintler beadlock
Overview: With 35s, only 4.10 gears, and a minivan engine it’s not as gutless as you’d think. Thanks to our relatively light wheel/tire combo we’re able to get away from stoplights briskly and maintain moderate grades without downshifting.
MPG Notes: Combined average of 17.8 mpg, with highs of 19.3 mpg on long freeway trips
Recoup $10,000 30 mpg vehicle @ $3.50/gallon: 8.3 years

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