What's Your M50 or S50 E30 Mpg??

[BBDirtbiking]

I can't believe people are running a 2.93 with a G240 or a G260... Haha.

[avery0829]

M52 OBD1 + ZF + 2.93lsd with a mix of freeway and city driving 25mpg

[nando]

Aerodynamics KILL E30 MPG at 70+ MPH. On a modern car, the difference between 65 MPH and 80 MPH is a 15%~ reduction in fuel economy. Now imagine what it is for the E30 with its awful co-efficient of drag (0.38+). E30 M3 body style doesn't have this problem with aero CoD of 0.32~.

Things to improve E30 aero:

Lower car ride height
Front valence/spoiler
Underbody panelings to reduce drag

Unfortunately E30 aero is like a brick. :\ And it doesn't help that S50/S52 are high compression engines which means that they engine brake rapidly and can't coast at all at freeway speeds.

The ironic thing is that an E30 with a turbo M50/S50 etc with lowered compression would actually get better MPG due to the turbo increasing fuel efficiency (especially while cruising) and the ability to coast further/longer thanks to lowered compression.

where'd you get .38? is that for a non-sport model? diving board eta?

I've seen anywhere from .34-.35 for a 325is (late body). the trunk spoiler actually decreases drag by about 2% according to BMW.

you can laugh but BMW did actually wind tunnel test the later E30s.

[VinniE30]

I think its a good idea to state whether or not the car was previously a 318is.

You guys with the 325i's have a larger capacity tank, ya'll have more range!!

The size of the tank does not affect gas mileage. Unless you count the negligible factor of both having a full tank and the larger tank carrying slightly more weight. Things like driving style, mods, and what people consider to be city/mixed/highway and other factors are what account for the differences.
So why would it matter if it was previously a 318is in terms of gas mileage?

[dude8383]

I think its a good idea to state whether or not the car was previously a 318is.

You guys with the 325i's have a larger capacity tank, ya'll have more range!!

[Rsully70sev]

Damn, I just calculated my last fill up and I got excellent gas mileage. It was about 50/50 city/highway and I got close to 30mpg on a S50 ZF 2.93.

I filled up, drove around 130 miles on the freeway, then ROMPED it hard around town for another 100 miles. (My gas gauge doesn't always work so I always make sure she's filled up) so I thought "Eh, 230 miles, I'll fill up just in case"....I only filled up 8 gallons on the dot.

230/8= 28.75mpg

[evandael]

nothing about a turbo increases fuel mileage. only for comparative power levels, perhaps (ie, a 400hp boosted six cylinder vs 400hp n/a v8 )

[DisgustipatedAP1]

I have a few thousand miles on my swap now and am pretty pleased with the mileage:
24-26mpg mixed driving
28-31mpg freeway (~65mph)
calculated from odometer to fillup since my OBC says 50+mpg:???:

It goes down real fast if I go over 70mph or have my bike rack on the roof. I got 24mpg last weekend, all on the freeway going 75 with two bikes on top.
My last car was a TDI and it made very little difference if I had a rack on, going 80, and the car fully loaded with the AC on... maybe 2mpg difference.

Current car:
87 325is, m52b28, zf320, 3.15 gearing, stock tire size, H&R sports.
Headers, OBD1 manifold, Light Fly, Tuned for 91oct.

-Steven

Aerodynamics KILL E30 MPG at 70+ MPH. On a modern car, the difference between 65 MPH and 80 MPH is a 15%~ reduction in fuel economy. Now imagine what it is for the E30 with its awful co-efficient of drag (0.38+). E30 M3 body style doesn't have this problem with aero CoD of 0.32~.

Things to improve E30 aero:

Lower car ride height
Front valence/spoiler
Underbody panelings to reduce drag

Unfortunately E30 aero is like a brick. :\ And it doesn't help that S50/S52 are high compression engines which means that they engine brake rapidly and can't coast at all at freeway speeds.

The ironic thing is that an E30 with a turbo M50/S50 etc with lowered compression would actually get better MPG due to the turbo increasing fuel efficiency (especially while cruising) and the ability to coast further/longer thanks to lowered compression.

[SHunter]

I have a few thousand miles on my swap now and am pretty pleased with the mileage:
24-26mpg mixed driving
28-31mpg freeway (~65mph)
calculated from odometer to fillup since my OBC says 50+mpg:???:

It goes down real fast if I go over 70mph or have my bike rack on the roof. I got 24mpg last weekend, all on the freeway going 75 with two bikes on top.
My last car was a TDI and it made very little difference if I had a rack on, going 80, and the car fully loaded with the AC on... maybe 2mpg difference.

Current car:
87 325is, m52b28, zf320, 3.15 gearing, stock tire size, H&R sports.
Headers, OBD1 manifold, Light Fly, Tuned for 91oct.

-Steven

[Leo_328i]

Fuel efficiency is king, though. And it's not like only slow cars get good mpg: a 997+ 911 Turbo is AWD, 4 seats, twin turbo, makes 500+ bhp and yet gets 26+ mpg on the highway according to the EPA. :)

Truth.

One of the most important factors in a car is smiles per gallon!

[butters]

I don't rely on the econometer. I say indicated because my speedo is off due to wheel diameter.

How do you calculate instantaneous mpg then?

Also, the speedo is off from the factory. GPS confirms the needle is about 5mph high around highway speeds, with stock tires.

I'm not sure I buy 30+ mpg claims even with tall gearing. I have ZF/2.93 with my S50 and in mixed non-freeway driving I see about 23mpg. I'd guess mayyybe 28 if I really tried on a road trip. The engine is rebuilt, too. In my M42 days I could get 28 mpg with 90% freeway driving, not really trying that hard. I fail to see how a 3L 6-cylinder could exceed that, let alone match it, even with some slight gains in technology related to efficiency in the progression of BMW development. I suppose I'm a skeptic.

[hoveringuy]

M54. G260, 3.25 diff.

I get 22/28.

[DisgustipatedAP1]

seems kinda rediculous to car about MPG in a swap...

Fuel efficiency is king, though. And it's not like only slow cars get good mpg: a 997+ 911 Turbo is AWD, 4 seats, twin turbo, makes 500+ bhp and yet gets 26+ mpg on the highway according to the EPA. :)

[Robotin]

seems kinda rediculous to car about MPG in a swap...

[e30austin]

Vanos M50 here with G260 and S3.73 final drive.

Avg freeway cruising speed is 69mph (to keep it out of VANOS) and I can usually get about 25+ mpg when babying it in 5th. In town, I'd say probably around 20 mpg.

At $4.50 p/ gallon, $20 gets me 4.4 gallons. I can get about 100 miles out of $20, which is roughly 23 mpg mixed. I'm sure if I was a little nicer in town, I could get 25 mpg average.