does a 5speed get better mpg than an auto?

[heiman5]

hey I was jsut wondring because I have an auto and i only get like 14 mpg....i dont do much free way driving like... 5 out of my 10 miles per day...:D and i do not drive spiritdly just school and back...calmly. I was just wondering if my auto is robbing my mpg cause I was thinking about a 5speed swap anyways and if I will get better mpg in a 5 speed then i will deffenetly do it. If the tranny has nothing to do with mpg then wtf is up with 14 mpg????

[Jarvis]

5 forward gears (manual) vs. 4 forward gears (automatic)? manual 5spd wins for both gas mileage and overall acceleration.

Generally, automatic transmissions also cause more drivetrain power losses than manuals do. So with the auto you have to make slightly more power to do the same speed.

In every manual car I have owned, I have pulled off better than the EPA estimate for gas mileage. All the autos I have driven do about what the EPA suggests, or worse.

[nando]

on longer trips though the auto will win; the .72 overdrive ratio and locking torque converter pretty much nullify any advantage a 5 speed has. the EPA rating for my car on the freeway is 21mpg, I usually get about 26 and not at low speeds either (~80mph). My average is about 21, but in the city I don't do so good with a lead foot (18).

the number of gears doesn't really mean much, 5 speeds basically have 3 gears for the auto's first two (better acceleration), but 3rd in an auto is the same ratio as 4th on a 5 speed (1:1) and the overdrive gear on a 5 speed is tighter (.83) so at freeway speeds your RPMS can actually be higher (given similar rear diff ratios).

[heiman5]

most of my driving is cityish...suburbs 35 mph roads stoplights here and there and like a 4 mile freeway drive each way.... and I only get like 13.8 and thats not using lead foot accel....could there be a larger problem that i am not seeing

[PeaveyBassist]

Yes, you should be getting a lot more than 13.8. I got around 20-21 in my 325i flooring it from every stop light through 1st and 2nd gear, then going to 5th and cruising around 40mph.

Will

[heiman5]

any ideas?

[blueapplesoda]

same here....did usu maintinence, except for o2 sensor. 5 spd, maybe like 13-15ish mpg on a good day, just driving to school, lunch, then back home.
Wtf.

[heiman5]

i feel ya same type of driving and milage is shiiiiiiiiiiiiiit
home--->school
School----->home

[PУCCKAЯ_e30ka]

change your cap+rotor, clean injectors... hmmm... change your air filter.
P.S. what is a good injector cleaning fluid? The ones which you add to your gas when fill up... Just for some minor cleaning....

[65Matt]

I have used techron, and Lucas Oil FI cleaner seems to work even better. If you have access to a scan tool, scan your engine to see what it needs. Check the coolant temp sensor, it will run rich when this sensor goes bad.

[DaN]

How are you calculating mpg?

[browntown]

LUCAS FI Cleaner is the only way to go, most injector cleaners are just alcohol and do more harm then good.

[heiman5]

what my obc says

[KenC]

what my obc says

I wouldn't rely too heavily on it. Do some simple math and figure it out with the trip odometer.

[Rob]

try actually calculating your MPG. Next time you fill your tank, reset the trip meter, then drive as normal. Next fill up, note the # of gallons, and number of miles since last fillup. Miles divided by gallons=MPG


The worst mileage I've gotten in my 318 is 27mpg, I usually average between 28-31.