Tips for Improving Mileage, Most of Which Simple

[bmwman91]

I found another one...a little odd.  I noticed it on my routine 85 mile drive tonight.

Drive barefoot.  You have waaay better control of the throttle without shoes.  Minor corrections are easier to do this way.

[b318isp]

There is no way I can imagine getting anywhere close to 35mpg even on straight highway trips.

Three years ago, I won the annual BMW Car Club Ireland economy run - 39mpg over a varied 110mile course.

The following year I was runner up, with mpg in the high 38s.

In both cases I wasn't dawdling, I was even second fastest when I won! Near 50-60mph, my econometer can be hovering around 40-50mpg.

[Alpine003]

In both cases I wasn't dawdling, I was even second fastest when I won! Near 50-60mph, my econometer can be hovering around 40-50mpg.

This is great. Maybe I'll have the patience to drive like a normal person on the highway some day but right now, that would be hard to do.

BTW, I guess you can even get skinnier and taller tires(and or change rear end gearing) if you want that last bit of mileage as well.

[sheepdog]

I found another one...a little odd.  I noticed it on my routine 85 mile drive tonight.

Drive barefoot.  You have waaay better control of the throttle without shoes.  Minor corrections are easier to do this way.

And illegal in most states.

[Nick_318is]

^in the summer whenever i can I wear flip flops, I can't drive in flip flops so i drive bare foot, I love driving bare foot.  Heel toeing is a little harder but can be done.

I have just trained myself to put them back on should a cop ever pull me over.

[bmwman91]

And illegal in most states.

Indeed, I only do it when it is a case of the following quote.

^in the summer whenever i can I wear flip flops, I can't drive in flip flops so i drive bare foot, I love driving bare foot.  Heel toeing is a little harder but can be done.

I have just trained myself to put them back on should a cop ever pull me over.

I do not really see a reason for it to be illegal, honestly.  You get way better feedback barefoot...I know the reason is supposedly that you cannot hit the brake as hard barefoot.  I do not find that to be true though.  I suppose some might find it hard.

[strad]

Driving barefoot is not illegal.  Not in the states I've lived in recently anyways (CA, NV, WA).

[highlandmiata]

stop your engine if you are stopped for more than 10 seconds. It takes less gas/pollution to stop, and then start, even for that short a time.

[twinpop171]

Hmmm, I see that you have Bav Auto Performance Coils and a performance rear muffler. I wonder how much of an effect these can possibly have on higher rpm highway steady state cruising... There is no way I can imagine getting anywhere close to 35mpg even on straight highway trips.

The Bav Auto HP coils were worth the $$ IMO.  They added noticable power/pull in the lower RPM range right away (where the m42 needs it).  I think it definitely helped with the increased mpg while driving in slower moving traffic on the interstate.  I mean this by requiring less throttle to re-accelerate when cars in front of me were slowing down and speeding up.  The mpg guage was not dipping as low as it was previously when re-accelerating.

On previous trips the car got 27-30 mpg and 36 mpg only once (fluke?) while driving ~the same speeds. I haven't checked the mileage with driving locally though.  Previously it was 23 mpg with some hard driving and 27-28 with relatively normal driving.
Dan.

[Alpine003]

The Bav Auto HP coils were worth the $$ IMO.  They added noticable power/pull in the lower RPM range right away (where the m42 needs it).  I think it definitely helped with the increased mpg while driving in slower moving traffic on the interstate.  I mean this by requiring less throttle to re-accelerate when cars in front of me were slowing down and speeding up.  The mpg guage was not dipping as low as it was previously when re-accelerating.

On previous trips the car got 27-30 mpg and 36 mpg only once (fluke?) while driving ~the same speeds. I haven't checked the mileage with driving locally though.  Previously it was 23 mpg with some hard driving and 27-28 with relatively normal driving.
Dan.

Thanks for the feedback. 27-30 is inline with what I normally get on highways going that speed and between 23-25 mixed driving.

I wonder if the Bav Auto Coils has any advantage over the COP conversion using OEM coils. Hmmm.... Anyone experience any similiar results using the COP conversion instead as twinpop?

[sheepdog]

Driving barefoot is not illegal.  Not in the states I've lived in recently anyways (CA, NV, WA).

Actually, I am pretty sure California is one of them.

I have heard various reasons as to why though, the consistent part is usually  accidents, be it you getting in one they do not want you getting out and walking on glass or because some people are stupid enough to leave the shoes in the footwell and get stuck under a pedal. Either way you go could be bad, in an accident the shoes could go flying leaving you nothing to walk out with.

[bmwman91]

Phew, good thing I got that robotic leg conversion!  I don't know why I even drive anymore, I can run 90mph with them on beer & corn dogs, which is cheaper then gasoline.

[christophbmw]

And illegal in most states.

correction, it would be unlawfull by driving barefoot. it is only illegal if you get caught. (illegal means a state law enforcment agent has beeninvolved).

1) Shift at 3000RPM when accelerating.
 - This one is tough, I know.  However, friction within the engine is due mainly to a couple things.  One is the fluid resistance inside from the oil and coolant being pumped, and it increases exponentially with engine speed.  The other is from the piston rings rubbing on the cylinder walls.  As RPM gets higher, they rub more times per second, increasing the amount of drag versus shifting and continuing to accelerate at a lower RPM.  The fluid resistance also plays a part in the transmission due to the input shaft and the gears it is coupled to.

excellent write-up, i agree with everything you said except #1, by shifting down low you will not get bettter gas millage (it might be the same). the internal combustion motor is most efficient at its max HP rating so shifting at say 5 grand would be best for are motors untill you are up to speed, i personally shift at around 4 but if im accelerating uphill i will wait untill 5 grand. i have noticed i get about the same gas milage by doing so then i would if i shift at 3 grand. try it, just my 2 cents.

[bmwman91]

On a carbureted car, this might be true.  On our cars, the control system is a closed-loop feedback system utilizing the O2 sensor.  With the AFM and O2 sensor, the motor can inject the proper amount of fuel to account for the changes in volumetric efficiency over the engine speed range.  As such, it can maintain a stoichiometric air/fuel ratio at all times in closed-loop operation.  I will admit though, shifting at 3000RPM in any gear below 3rd on the M42 is infuriating.  I shift at 4K in first always, out of consideration for other drivers.  Second gear calls for 3-3.5K shifts as well.

[b318isp]

excellent write-up, i agree with everything you said except #1, by shifting down low you will not get bettter gas millage (it might be the same). the internal combustion motor is most efficient at its max HP rating so shifting at say 5 grand would be best for are motors untill you are up to speed, i personally shift at around 4 but if im accelerating uphill i will wait untill 5 grand. i have noticed i get about the same gas milage by doing so then i would if i shift at 3 grand. try it, just my 2 cents.

I think your econometer may tell you otherwise! Engine is most efficient around peak torque, not peak power.

However both a low throttle opening and/or too low revs when the car is working is not good for fuel economy.