Highway fuel economyeconomy

[corey2140]

For the 35i, at what highway speed does the car get the best MPG/fuel economy? I'd like to set the cruise control to that speed.

[richsnuc]

80

[BuddhaPilot]

I understand trying to get the most out of a tank, but please tell me you didn't buy a 135 because you thought it might be good on gas Unfortunately, it seems to get better at faster than legal speeds- like 80-90 mph.

I tend to see the same combined average of 23.5-24.5 irregardless of whether I'm doing the speed limit or 15 over. Observe the instantaneous for abit and you'll see it settle around 31-33 mpg at pretty much any speed between 65-80. I did a stretch at let's just say it somewhere north of that speed and watched my average increase to nearly 26 in a 15 mile period. I've seen 29 on long highway only trips.

While 24 mpg doesn't sound great to a lot of people, it's pretty damn impressive on a car rated at 300/300. One my relative's 1959 283cuin/300 hp Vette gets about 15 mpg. We've come along way to say the least!

[JefryHorizon]

funny how at 80-110 mph you get sublime mpg since the car is traveling a reasonable distance per hr and using the same amount of gas at 60-80mph..

just my 2 cents and a video..

[slim_e90]

Can't touch Top gear logic!

[1ToBeOn2Wheels]

Originally Posted by BuddhaPilot

I understand trying to get the most out of a tank, but please tell me you didn't buy a 135 because you thought it might be good on gas

It says he drives and X3 and only mentions his car as a "35i" so I doubt he's referring to a 135, which also means he's in the wrong forum. Maybe since we have the same engine, he thought we'd have some input.

[TX78666]

On the highhway, 50 mph is where I have seen the best. I get well over 30 mpg at that speed - possibly 35 or more. Who wants to drive 50 MPH? As soon as things open up, I'm doing 70-80 and getting about 28-29.

[RoundelM3]

Anything under 3K rpm in top gear should return decent mileage. My 335i with mods returns 28-29MPG at 70-75MPH.

[J0E]

Just play it safe and go with the speed limit. If you are setting your cruise at 55 on a 65 just to see an extra half mpg...

[ptack]

I'm more interested in timeage that mileage so less time is more important than less fuel.

[corey2140]

Originally Posted by 1ToBeOn2Wheels

It says he drives and X3 and only mentions his car as a "35i" so I doubt he's referring to a 135, which also means he's in the wrong forum. Maybe since we have the same engine, he thought we'd have some input.

Yeah i made the post from my iphone and didn't realize I was still on the 1 series forum. I meant to post it to the x3 forum.

[brusk]

I know it's nice to get better gas mileage but please don't go under the speed limit or hold people up just to save a few bucks. I wish people would do the math as you aren't saving that much money per year. If you want better gas mileage tail gating is the best results. This can be done at any speed and the results are usually good. And before I get any complaints remember that technically most on the highway is tailgating by the 3+ second rule so use judgement depending on driving conditions and roads. I've picked up as much as 5 mpg by getting behind SUV's and fast moving truckers while still maintaining 70+ MPH in mid size V6 powered family cars.

[rogm]

The 2 mpg is not worth it for me to drive at 55mph... I cruise at 90.

[gnpower]

cruising at 75mph for 3 hours I managed 28.5mpg

[JefryHorizon]

Originally Posted by rogm

The 2 mpg is not worth it for me to drive at 55mph... I cruise at 90.

indeed....

[jsmonet]

Originally Posted by gnpower

cruising at 75mph for 3 hours I managed 28.5mpg

90-95 for an aggregate of 5 hours got me 27mpg.

flying down the highway in the middle of nowhere without worry of deer is quite nice

[BFD99]

Wow you guys must drive with a soft foot, or have better fuel where you are at. On a good day I see about 23mpg. Usually I see around 17-20 on the odometer. Are any of you guys hand calculating MPGs or just going off the computer? Curious to see how accurate it is.

[roo97ss]

Originally Posted by BFD99

Wow you guys must drive with a soft foot, or have better fuel where you are at. On a good day I see about 23mpg. Usually I see around 17-20 on the odometer. Are any of you guys hand calculating MPGs or just going off the computer? Curious to see how accurate it is.

i'm with you. straight highway trip i see 27-28, my commute which is highway, some 50 mph back roads and a little city i get 20-21 averaging about 40 mph.

[tazzydnc]

Originally Posted by TX78666

On the highhway, 50 mph is where I have seen the best. I get well over 30 mpg at that speed - possibly 35 or more. Who wants to drive 50 MPH? As soon as things open up, I'm doing 70-80 and getting about 28-29.

Yeah that's what I've noticed too. At whatever speed in the top gear where the tach is at 1400. For the 135i at least

EDIT: ok there's a difference between highway speed and interstate speed. I dunno what the EPA is referring to when they say "highway", but when the speed limit is 45, going 50mpg seems very reasonable.

[gwhiz]

So how much of an impact does driving in "sport" mode have on this whole discussion? I haven't done any experiments with it but I can't imagine that there is no impact.

[TX78666]

Originally Posted by tazzydnc

EDIT: ok there's a difference between highway speed and interstate speed. I dunno what the EPA is referring to when they say "highway", but when the speed limit is 45, going 50mpg seems very reasonable.

Unfortunately, I mean interstates and state highways, with speed limits of 70-75. Sometimes traffic is just right, to get everyone going a steady 50 (no slowing down and speeding up and slowing down and speeding up). That's when I see great mpg, and when traffic clears, I think, for a half second, that maybe I should drive 50 all the way home, and see how long a tank lasts. Then, I remember how good it feels to put my foot in it...