BMW M3: "The optimal speed for fuel economy in this car seems to be around 80mph"

[NoCO2]

Originally Posted by diesel_john

that must be 80 kilometers, the data would almost make sense then.

I'm with John on this one, 80km/h would put it at around 50mph and that would make a lot more sense for the FE to be the highest. Also, 120Km/h then would put him at around 75mph and that would be a much more reasonable speed to expect someone to drive on a public road.

I smell a fish, anyone else?

[MetroMPG]

Nope, I do believe he's reporting MPH. Lots of chuckles in the thread about it, like "all runs done in mexico" etc.

[JJW]

He says "90mph" in one of his comments, so that's not kph. I'd still like to know where, honestly, traffic "cruises" at 80 anywhere in the northeast. I think its a psychological effect of traveling that speed, noticing other cars staying in your group, and assuming everyone is going that fast while you disregard all the people you are flying by.

What he means by "gears use more fuel at any speed" is that if you change the final drive gearing higher for better acceleration your fuel mileage will go down. That's why its under mods.

[sickpuppy318]

My mom has an '06 Jeep Cherokee and she seems to think that she gets the best mileage at 65mph. Of course, i always call B/S on that and tell her she doesn't know how to drive anywhere near reasonably. We used to live on long island, and on the LIE flow was at least 80 even though it is a posted 55. I think its a New York thing that she thinks 65 is reasonably slow and her cherokee is reasonably small!

[RH77]

Originally Posted by sickpuppy318

My mom has an '06 Jeep Cherokee and she seems to think that she gets the best mileage at 65mph. Of course, i always call B/S on that and tell her she doesn't know how to drive anywhere near reasonably. We used to live on long island, and on the LIE flow was at least 80 even though it is a posted 55. I think its a New York thing that she thinks 65 is reasonably slow and her cherokee is reasonably small!

Yeah, I get the same from my fam. People have to be willing to change or accept the Science behind the change. Meanwhile, there's nothing to do but report your own savings She might come around after a while...

RH77

[kevlar]

Originally Posted by RH77

50 and 60 mph is indeed missing. But (GASP!) You can't drive an M3 that slow!

RH77

It would be quite a kick in the pride, but I'll bet it would do good around fifty in fifth

[dremd]

I have to say that the Supra with tall gears, big tires, cold ambient temps, undertray, optimal fe speed did appear to be in the 80~90 mph zone (was 2200~2400 rpm with decent load) With the 4.30's in her now it's probably around 40mph (guess).

However I did pull several 33 mpg in town tanks on it last summer; even with 285's out back and 245's up front. Just watch the boost gauge, turn the motor off as much as I could, run lots of PSI in the tires. "Normal" driving gives 15~17 mpg in it now. I don't want to Eco-mod it nor hypermile it, as long as I burn less than 2 tanks per year (3/4 tanks burnt so far this year) I don't care.

[sickpuppy318]

i'm no "expert", but a little P&G with boost smells like a fried turbo. Does that supra have and oil cooler like the turbo 300zx did?

[dremd]

Originally Posted by sickpuppy318

i'm no "expert", but a little P&G with boost smells like a fried turbo. Does that supra have and oil cooler like the turbo 300zx did?

Factory oil cooler sucks, I just chunked it. M-1 Red Top Changed every 10 tanks of Fuel. (100 miles at the track, 250 "normal"and 450 in "Hypermile"

I never did P&G per say. Just let it idle down, see 1000 deg EGT and shut it down.
Just running an upgraded CT26 $400 for a new one so wasn't a big deal.

I was driving 85 miles per day in some of the worst stop and go traffic I've ever dealt with. 0-50-0-50-0-50 every 1.5~3 miles. I would run it up to speed at "0" psi idle it down, shut it off coast to stop; repeat. Sometimes I got to to not quite stop which helped out hugely. It was alot of work. But on the + side I have a vac resovoir + pump (for longer turbo Burnouts at the Track I would push through the lights and be disqualified); didn't really matter on the street.

[sickpuppy318]

sound cool though, i never got to take my Z to the track, but it was an N/A and i got 30+ MPG out of it. I drove the snot out of it for a couple years, couldn't kill it if I tried, and try i did. I would imagine the supra is the same way, even with a turbo.

$400 for a new turbo still sounds like quite the headach, and 1000F seems like it would still cook some oil