Yeah, I agree. In my humble opinion, the four factors that influence fuel economy are:
Vehicle weight
Gearing
Engine displacement
Aerodynamics
This ignores driver behavior. I changed the drive ratio in my 1970 Mustang from 3:00 to 3:50 and noted two things. I raised the engine RPM and sucked gas like a B#$stard.
It's funny because I'm a Jeep owner newbie and after driving my 04 TJ (5sp, 6 cyl) I couldn't help but think -- 1st gear is geared so low, it's almost useless. For folks that don't off road regularly (I've never, but am considering going this year) why the hell doesn't Jeep offer a "road gear" option?
I'm sure that's a stupid question. But if they did, I'd bet gas milage for the platform would be raised significantly. At 70MPH with stock road tires, my six is turning 2700 RPM. And in all of the lower gears, the driveline ratio is so high my tach looks like a windshield wiper turned to "driving rain" as I shift from 1st to 4th.
Anyway, I asked about parts cost to change out the final drive to a 3:07 -- the response was "thousands of dollars." The way I analyzed that is this:
If I spend $2000 to give my beloved Jeep longer legs (each engine crankshaft revolution propels the Jeep further on down the road) I might improve the overall fuel economy -- what -- 10%? Let's guess 20% as an optimistic (and probably unreasonably optimistic) estimate. Well, my TJ gets 15miles per gallon. So by my screwed up math, the $2000 gets me an additional 3MPG. If I drive 10,000 miles per year, at 15MPG, I would normally burn 667 gallons - $1667 at the lowest California gas price of $2.50/gallon)
Well, if I spent the money to improve gas milage, the math shows that with the 3MPG improvement (to 18 MPG) reduces my yearly fuel use to 556 galloms ($1390 annual fuel cost). The difference is $277 per year. Yikes! I'd have to drive the car 7.2 years just to break even on the $2000 investment!
And of course, it will cost more than $2000 and the fuel economy improvement will certainly be less than 20%. Not to mention the affect on warranty, loss of off roading capability and the fact that there's serious work to change out the gear.
Personally, i think we're headed toward a permenant $4-6 per gallon fuel price, so as that occurs, I may reconsider. (Or go get a Porsche 914 for $3000 as a daily commuter
)
Anyway, belive you me, lots of us have had the same thought about improving gas milage for Wranglers. Ultimately, the deal is this: No car does it all. The Wrangler, in my book, comes the closest, and it's a beautiful automobile. Focus on it's good points -- a fun, rugged, non pretentious piece of American automotive excellence that matches Siggie's personality.
Gas milage be damned!
