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Is a 4 cylinder really THAT much more fuel efficient than a 6?

3K views 20 replies 20 participants last post by  CHRRRIS 
#1 ·
I've been looking at various websites and according to them, the highway MPG is identical, while city driving will give the 6 cylinder 2-3 less miles to the gallon. Anyone that has had both can give me some info?

Oh, and right now, I'm looking at a 4" lifted 6 cylinder with 35's and 373's. How many miles to the gallon you think this gets? Would it be much better than it would get if it didn't have those tires?
 
#3 ·
No matter what, there isnt going to be much of a difference. With that said, gearing is what is going to make the most difference IMO. If 2 jeeps (one a 4cyl, one a 6cyl) had 35" tires and 4.88 gears, the six cylinder isnt going to work as hard to move the tires.
 
#8 ·
I think your milage will be between 11 and 15..........average. Being in the position your in right now, I would "go with what you got!" A 4 cyl. as a DD with 31"s and 4.10"s will give you better by far(if it's kept that way), but it does not sound like that is your intent ! Look at my sig., I have an XJ for a DD and tweaked it for MPG. I'm getting 27 average, and that took some time and money. It is a hobby for fun and I just wanted to see were I could get it to.
hvac59
 
#9 ·
My four cylinder averages 20 MPG around town, and has hit nearly 21 MPG on numerous occasions. After replacing my distributor and wires, I expect that to go up. I haven't done much highway driving with it, but I expect it to be in the 19-20 MPG range.

My six cylinder has hit 18 MPG around town, but I suspect that it averages about 17 MPG. On the highway, it is consistently 19 MPG.

These are both stock setups. With a 4" lift and 35" tires, you increase the rolling and wind resistance, and MPG goes right out the window.
 
#11 ·
I still average 20 mpg on a tank if i just drive it to work. (18 miles of country 2 lane road and 1.5 miles of city). If it get on highway it drops to 18.5-19.5 mpg.
Mine is a 4.0L 5 sp and has 31s and 3.73. If you want mpg shift it at 2200rpm.
It works for me.
 
#12 ·
if miles per gallon is your main concern you may want to consider a different
vehicle.

if you can deal with real world average mpg of about 14mpg and you
want to have more fun than should be legal than buy a jeep.

Brian
 
#14 ·
My 4cyl. with 33's gets around 15-18 MPG depending. It doesent bother me. Its dependable and gets better MPG than my 79 Z28. I have to agree with 7.7stroker - it should be fun per gallon!!
 
#16 ·
Very little difference stock, and the bigger tires etc you go, the less difference you'll notice. Probably almost none in some types of driving. I get 15-16 mpg city with my 31 inch tires. Harldy worth buying a 4 cyl for just to save the 1 or 2 mpg. I just bought mine because 4s are cheaper and its a second vehicle( 3-4k miles year).
 
#17 ·
I was thinking about this the other day when i heard that "Consumers are makinga shift to 4 cylender engines over 6 and 8 cylenders because of high fuel prices"...

if you have a 4 cylender with a properly geared 6 speed trans and some form of a mid range gear setup (4.10 is midrange right?) and are absolutely anal about watching the tach to shift, then yes, youll get good mileage. If you don't, which most paeople don't cuz they don't even know what you mean when you say "gears" then your 4 cylendar isn't doing you squat for mileage, and the way most everybody drives (floor it at a green light, stomp on the fat pedal at the reds) isn't helping either.

I'd have to say that the 6 would be better with a proper drivetrain setup. Without the need to wind the 4 cylender out as high, and the right setup you'd probably get about the same, MAYBE a bit more.

If you think about it they eventually equal out:
Small motor= high revs to get speed=more fuel
Big motor= low revs for speed BUT more pistons to use fuel

Thats my :2c:
Anybody else?
:popCorn:
 
#19 ·
I thought I'd be saving money at the pump when I bought my 4 banger. I bought a 4 cylinder '01 with 18k mi, Just off of lease from a dealer who was also selling a 98' Sahara with 87k for 3 grand more. At the time I thought I was making a good decision. But it costs me almost three dollars at the mere sight of a steep incline. Go with the six.
 
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