How Bad Do Gears Kill gas mileage?

DTMach1 · Dec 4, 2005

TurbLu said:
Just so you guys know, fuel consumption isnt just based on rpm. Its based on how much fuel it takes to keep the vehicle moving at the rate of velocity you've chosen for it. zzzzzzzzzzzzthis is why cars with 4.10 gears can achieve similar to better gas mileage than cars with stock gearing. Especially in an area with alot of hills and slopes. The car with the lower fd will have to modulate the gas the pedal alot more than a car with a higher final drive ratio. Remember tourqe is multiplied by the FD so you have more tourqe to use at the same level of throttle than before. Thus alot less load on the engine at the same speed and incline.

yeah its not because I'm in 5th 80% of the time driving around town, where-as before I would've been in 4th or even 3rd....(just remember OD=wheels turning faster than motor therefore increased fuel economy)

fact of the matter is...if you're turning 3000rpm consistently for 10 minutes and then turn 2000rpm for another 10 minutes you would consume more gas at 3000rpm than you would've at 2000rpm...so I would say, yeah, RPM is a major factor in MPG.

If I spent all week driving back and forth to work in 4th gear, never shifting into 5th like I normally would, I guarantee my MPG would drop 2points.

TurbLu · Dec 5, 2005

Not to argue with you but 4th gear ratio x Rear End Final Gear Ratio is alot higher than 5th gear x Rear End Final Drive Ratio. The true test would be to drive around town in 4th gear on both cars at the same speed and then see who gets better gas mileage. Im not saying RPM isnt a factor. Just saying it only applies to some of your mileage concerns.

DTMach1 · Dec 5, 2005

TurbLu said:
Not to argue with you but 4th gear ratio x Rear End Final Gear Ratio is alot higher than 5th gear x Rear End Final Drive Ratio. The true test would be to drive around town in 4th gear on both cars at the same speed and then see who gets better gas mileage. Im not saying RPM isnt a factor. Just saying it only applies to some of your mileage concerns.

of course it is...4th gear is your 1:1 ratio where the 5th gear will be your lowest(OD)...depending on trans would be somewhere around .62-.68...so no matter what your rear gear ratio, the tires would be spinning faster than the motor.

TO be honest If gas prices weren't so damned expensive I'd try the 4th gear thing...but **** that!!

thomas91169 · Dec 5, 2005

who the **** cares? who buys a mustang and worries about their mileage anyways?

Stang|ess · Dec 5, 2005

87 costs 2.65 and when i get 15 mpg it matters. Not everyone can be mister moneybags like you and not give a ****, but to the average joe, mpg matter.

On that note, do you guys use ac or what? I'm getting 15.8 mpg and its a combination of highway, and mild highway traffic.

BooWFO · Dec 5, 2005

I need to check I just did a 240mile trip this weekend on 1 tank still got about a 1/4 tank in the car running about 77 mph the whole way. With 4.10's in a 04 5 spd.
In my normal driving which is combo city/highway/drag racing I get 20mpg. Last road trip I took running 80 the whole way I knocked down 24 and change MPG.
BTW with a 3650 tranny 3k should be 90mph.

Seraphitia102 · Dec 5, 2005

sgarlic said:
Still don't understang how you guys get 18-19 in the city. I get 14.9 consistantly.. and have since I drove it off the lot.

I even tried driving like a grandma and still get around 15mpg.

TurbLu · Dec 5, 2005

If your tuned check the tune your running. You'd be surprised how many tunned NA guys are running pig rich

Red35th · Dec 5, 2005

My brother and I have pretty much the same cars, except he has 3.73s. I still have the stock gears and I followed him back and forth from Dallas last summer. I was about a quarter-mile behing him the whole way, so there was no real draft effect.

I got 24mpg on the trip, he only got 21mpg. Both cars were on cruise, it was the same way on the trip back.

Proof enough for me to keep my stockers.

langod · Dec 5, 2005

I drive mostly suburban and back roads. Very little highway.
When I put in my 3.90s, I dropped about 1 to 1.5 mpg average. My last couple of tanks averaged out to about 19 mpg. And this is with a Predator tune.

007 · Dec 5, 2005

Red35th said:
I got 24mpg on the trip, he only got 21mpg. Both cars were on cruise, it was the same way on the trip back.

Proof enough for me to keep my stockers.

Oh God. In an auto too. Thats a retarded decision if I ever heard one. Sorry.crapola

wanta5.0 · Dec 5, 2005

Stang|ess said:
87 costs 2.65 and when i get 15 mpg it matters. Not everyone can be mister moneybags like you and not give a ****, but to the average joe, mpg matter.

On that note, do you guys use ac or what? I'm getting 15.8 mpg and its a combination of highway, and mild highway traffic.

I get 18-20 with mixed driving. Do you get on your car non stop?

TheDamned · Dec 5, 2005

I do 180miles with a full tank.... gettin gears would be DEADLY amnit:

03ghoststang · Dec 5, 2005

guys, guys come now DONT FEAR THE GEAR

Red35th · Dec 6, 2005

007 said:
Oh God. In an auto too. Thats a retarded decision if I ever heard one. Sorry.crapola

Considering how I'm happy with my ET and MPH it's really a non-factor. If I was NA I'm sure that I would want gears, right now they would do me virtually no good.

007 · Dec 6, 2005

Red35th said:
Considering how I'm happy with my ET and MPH it's really a non-factor. If I was NA I'm sure that I would want gears, right now they would do me virtually no good.

Youre ET on the juice is great (although gears would help that 60 foot), but you arent squirting that stuff all day long... All the rest of the time you are driving an NA car, and the stock auto gearing is WAY WAY too long.

03ghoststang · Dec 6, 2005

007 said:
and the stock auto gearing is WAY WAY too long.

that is so true that is why i got my gears now it revs faster into the power band and through the gear itself

saleen556 · Dec 6, 2005

I understand that gas prices have sucked lately but the mustang isn't meant to be economical.If I was worried about gas milage I would have got a honda.

96BlueStangGT · Dec 6, 2005

On the interstate going 75 at 2800 rpms with a T45, I get about 19-20 mpg. I don't care about gas milage though. The fun of driving a Stang is worth it.

sgarlic · Dec 6, 2005

Seraphitia102 said:
I even tried driving like a grandma and still get around 15mpg.

Bout time somebody finally admits they get crappy MPG too. Drive down here to Tucson and spend one tank of gas driving in normal traffic here.. I bet it's the same as me. I've tried every thing I could think of, nothing makes a difference.

I think the single best post in this thread so far has been the, "Who buys a Mustang and worries about the gas mileage."

How Bad Do Gears Kill gas mileage?

DTMach1

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TurbLu

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