BMW M5 Forum and M6 Forums banner
1 - 19 of 19 Posts

·
Registered
Joined
·
108 Posts
Discussion Starter · #1 ·
I am new to the M5, as well as 6 speeds. I was wondering what the optimal cruising RPM(freeway) is for our cars. :wroom:

Peace, Hector
 

·
Registered
Joined
·
13,016 Posts
Hector Lopez said:
I am new to the M5, as well as 6 speeds. I was wondering what the optimal cruising RPM(freeway) is for our cars. :wroom:

Peace, Hector
Hmm, optimum for what? Best gas mileage? Quickest from point A to point B? Not getting a ticket from the local constabulary? :) . For tradeoff between fuel economy and speed, I think the engine is happy around 2000rpm (didn't say it was the most fun). You can dial up the instantaneous consumption to measure. Of course, it is more fun to drive the car at the engine torque peak of 3800 in 6th gear!! :cheers:
Regards,
Jerry
 

·
Registered
2018 Alfa Romeo Giulia Quadrifoglio
Joined
·
72 Posts
Hey gsfent, I just bought my car from a place in west palm and had it shipped out to los angeles - nice area you guys have down there!

Hector, 2000-2300 rpm seems perfect for my car, anything under that produces exhaust drone - which I don't mind - but some may not like it.

-Matt
 

·
Registered
Joined
·
1,316 Posts
I run about 3k when I have others in the car. When I'm alone, I tend to run high 3's to around 4 so I get better throttle response when I want it

:noSMG:
 

·
Registered
Joined
·
108 Posts
Discussion Starter · #5 ·
Thanks for the replies. I guess what I am asking is if you are going to be at steady rpm's for a long drive, where is the car the happiest, and running most efficiently?:)

Peace, Hector
 

·
Registered
Joined
·
13,016 Posts
Hector Lopez said:
at steady rpm's for a long drive, where is the car the happiest, and running most efficiently?:)

Peace, Hector
Hector,
I still see two different questions. I think the car is pretty happy anywhere, the engine is tremendously flexible. If you want instant throttle response, I would say anything above 3k rpm would do that, as the torque peak is around 3800. Mash the gas at 4k or above and you will get your head snapped back.
For steady state cruising, I just slip the car into 6th gear. Not too many situations where you need to downshift, unless you are on a two lane country road. Clearly, the slowest rpm makes the car cruise most "efficiently".
Regards,
Jerry
 

·
Registered
Joined
·
13,016 Posts
matt310 said:
Hey gsfent, I just bought my car from a place in west palm and had it shipped out to los angeles - nice area you guys have down there!



-Matt
Matt
Sorry I missed you. Hope the transaction was smooth. WPB is a pretty nice place, even with all the current road consruction to catch up to the population explosion. Makes it harder for the Beast to stretch its legs! BTW, I have no exhaust drone with SS headers.
Regards,
Jerry
 

·
Registered
Joined
·
3,004 Posts
stick it into the highest gear you can and be happy with the power you have, and thats optimum :)


So if for you thats 90 in 3rd then so be it....or 6th at 80 for me. :)
 

·
Registered
Joined
·
1,461 Posts
I usually have people in my car with me so I tend to keep the RPMs pretty low.. but yesterday I drove by myself about 100 miles south on the highway and the revs didn't go under 3500. Taxed the fuel tank, but the Tubi was sounding awesome! I truly think that exhaust system sounds better with time.
 

·
Registered
Joined
·
251 Posts
This car is uncanny how happy it is at about *any* RPM. Most cars have one or two "sweet spots" where it just seems happy (no vibrations, good response, nice sound).

The M5 is simply happy anywhere from 1,800 to about 5,000 (it gets a bit raspy and noisy over 5,000).

With passengers who want "max luxury" I generally use 1/4 throttle maximum and shift at about 3,000 - 3,500. Smooooth as glass. Freeway cruising settles in at a quiet 2,400 or so (but I haven't learned the MPH:RPM relationships in top gear as others have graphed).

Nothing scientific, but according to the OBC it seems fuel economy is best during freeway cruising at 70 - 80. It doesn't make sense, as the lowest RPM without "bogging" the engine should yield the best economy - but that's no fun anyway :wroom:


Paul
 

·
Registered
Joined
·
105 Posts
Powerchip....

:byee55amg

Have these guys change your software and you will more enjoy the entire range of throttle response. The peakiness (I'm sure that's a word somewhere) was removed, and I now have consistent response at any throttle / RPM combination.

Added a lot to the driveability of the M5 in urban situations.

Bob
 

·
Registered
Joined
·
136 Posts
Best gas mileage at lowest RPM?

gsfent said:
Clearly, the slowest rpm makes the car cruise most "efficiently".
Regards,
Jerry
is this true? i've been meaning to post regarding this.

assuming level ground, no air resistance, etc, etc... which is more efficient?

cruising at a constant 70mph at 3000rpm in 5th gear, or 2300rpm in 6th gear?

sometimes i feel like 2300rpm is low and makes the engine less efficient. (of course, there is always enough power in the M5). or maybe i feel this way because the ground is not level and 3000rpm is more efficient to overcome this.

i guess the question is - is there an "efficient rpm band" for an engine? i think there is.
 

·
Registered
Joined
·
530 Posts
Spider:

Absolutely there is a band where fuel effeciency is highest. What that is on an M5 , I do not know, but from feeling out the car for a while, I am converging on about 3100 RPM. Intuition guides me to believing that it also occurs with the better torque producing areas of the RPM band.

A crude test might be to compare gas pedal depression in 5th vs. 6th at a given MPH. If the gas pedel depresses less in 5th to support the same speed (albeit higher RPM of course), then viola, effeciency is seen.

As for optimum cruising RPM, anything below 80MPH gets 5th, 80+ 6th. With this arrangement I can get about 21MPG.
 

·
Registered
Joined
·
136 Posts
Joe,
great. my crude tests show about the same. i tend to cruise around 3000rpms. but 21mpg.. wow!
actually, i might do that on highways, but my overall commute averages to 17mpg (70% highways, 25% traffic, 5% city). not too bad. it doesn't seem to vary much even if i drive it harder on the highways.

sport mode always on. i shift between 3500-4000rpms i think.

James
 

·
Registered
Joined
·
13,016 Posts
Re: Best gas mileage at lowest RPM?

SpiderSense said:
is this true? i've been meaning to post regarding this.

assuming level ground, no air resistance, etc, etc... which is more efficient?

cruising at a constant 70mph at 3000rpm in 5th gear, or 2300rpm in 6th gear?

sometimes i feel like 2300rpm is low and makes the engine less efficient. (of course, there is always enough power in the M5). or maybe i feel this way because the ground is not level and 3000rpm is more efficient to overcome this.

i guess the question is - is there an "efficient rpm band" for an engine? i think there is.
I used to think there is and had the same debate, especially with lower powered small engine turbo cars where you could run the engine so slow as to make it lug and thereby I assumed be less efficient. I saw a letter one or two issues ago in Roundel and the consensus from the pro's was that efficiency (here we are talking about fuel efficiency) was directly related to rpm. As a test, set the cruise at say 80 mph on level ground, and then run for 10 minutes or so in 5th gear after resetting the fuel consumption. Then do the same run in 6th. I am willing to bet that mileage improves in 6th. Same result at 60mph. But at say 40 mph, you are probably lugging the engine so I don't think any fuel efficiency is worth the strain on the engine.
With my headers and gearing, I get 27-28mpg at 60 in 6th gear, 23-24 at 80. I recently did a run to Key West where I got 480 miles on the tank and 25.2 measured mpg.
I am not necessarily advocating driving at very low speed in gears, just as a reference point for efficiency. My car seems relatively quick (right, Anita? :1: ), so I don't think the taller gearing hurts this car in anything but a drag race. My $.02 while I still have it before gas prices go up again. :crying:
Regards,
Jerry
 

·
Registered
Joined
·
136 Posts
maybe it is somewhere in between.. engine is more efficient at 3000rpms, but it needs to crank out more cycles which uses more fuel to travel a set distance.
so 5th @ 3000rpm will probably consume more fuel to drive 10miles than 6th @ 2300rpm for 10 miles, assuming level ground and no air resistance. :)
 
1 - 19 of 19 Posts
Top