Fuel Consumption

[Lacke]

Hi!

I have a M45 2006, and would like to receive advice on how to reduce fuel consumption.

Regards

Lacke

[BizAsUz]

Dont drive it...

I would say dont have a lead foot...(like me) try to drive normally... you burn more gas in stop and go areas...so if you live in one of those types of areas then...well....

[Ilya]

There is a thread in the FAQ on this topic. Tire pressure, maintenance, tires themselves (quality of them), filters, etc. all play a small role in the bigger package of MPG.

[EdBwoy]

Another unconventional thought ->If you drive at highway speeds, don't use cruise control. The 5 speed trans likes to get aggressive. Modulate speed with your foot and use hills to your advantage.
I have squeezed 27mpg out of the 03 m45 like that, but only 25 out of the 06 m45 (not too many hills to play with in Iowa). A/C blasting in both instances

[Larz]

Ed is right. I always believed that cruise control would electronically keep track of speed and supply fuel at the least possible amount to maintain that speed. Well, if it does work that way, then my right foot beats the crap out of my car's computer. Om my 07 M, the cruise control stopped working and before I could get it in to the dealer, I had to drive up to Tallahassee to referee a rugby match. On the whole, I averaged 2-3 miles per gallon MORE than cruise control did on previous trips. It's only 2-3 mpg, but consider an extra 2-3 mpg on trip of say 900 miles each way!
There really is no way to make a huge drop in MPG unless you strip the interior, remove the windows, lop off the roof, and make it into a four wheeled fuel tank. It's little individual tricks that add up.
Keep the windows closed - 5% better than open windows. Don't run the air/con if the temps aren't too high or low - anther 5%, etc. Don't coast to a red light - keep the foot on the break and don't switch to neutral at long lights - less fuel is burned IN gear than OUT of gear.
OR ........
Do what I do:
screw all that, just resign yourself that these are not fuel miser cars, do what you can and limit your spirited driving to sometimes instead of all the time.

[szh]

screw all that, just resign yourself that these are not fuel miser cars, do what you can and limit your spirited driving to sometimes instead of all the time.

That is my approach too.

Z

[EdBwoy]

...
screw all that, just resign yourself that these are not fuel miser cars, do what you can and limit your spirited driving to sometimes instead of all the time.

Sound advice here.

[Gunnar75]

Besides that fuel is really cheap in America! Your best fuel mileage will be about 45mph in top gear on flat ground windows up and no accessory on. Make sure you car is fully maintained, that will help too!

[The00Dustin]

Ed is right. I always believed that cruise control would electronically keep track of speed and supply fuel at the least possible amount to maintain that speed. Well, if it does work that way, then my right foot beats the crap out of my car's computer. Om my 07 M, the cruise control stopped working and before I could get it in to the dealer, I had to drive up to Tallahassee to referee a rugby match.

Cruise control is designed to maintain speed, not worry about fuel economy. That having been said, I think standard cruise control will most definitely get better mileage than your foot on flat roads. However, I suspect you were using intelligent cruise control, which is going to brake and speed up more aggressively than an intelligent driver would need to (for vehicles in front of you and around curves). Moreover, even if you were using standard cruise control, it will still accelerate more aggressively than an intelligent driver may need to when it encounters a hill, and the downhill behavior of my 2006 M with either cruise control mode is just sad, so it doesn't surprise me that some people could get better mileage with their foot. Personally, I use standard cruise control when driving on curvy/hilly roads, using my foot on the accelerator to prepare for a hill climb so as to prevent the aggressive behavior. I only use intelligent cruise control on 4+ lane highways, using my foot on the accelerator to prevent ICC braking when approaching a car in front of me. Finally, I take varying measures (depending on the hill) to avoid the downhill behavior I experience with both standard and intelligent cruise.

Don't coast to a red light

I think you should elaborate here. If you keep your foot on the accelerator right until you have to stop, you will most certainly be using more fuel. Additionally, if you were to start braking early and brake the whole way, I should imagine you would be wearing your brakes more while not saving any additional fuel vs coasting (while wind, engine, and transmission drag, which don't require additional fuel, would save your brakes some work).

keep the foot on the break and don't switch to neutral at long lights - less fuel is burned IN gear than OUT of gear.

I'd love to know where you got this information, and I'm wondering if it might have applied to carbureted vehicles vs fuel injected ones. When the brake is engaged and the transmission is in Drive, I would expect the transmission to have more moving parts and thusly more resistance. Moreover, when I put my 2006 M in Neutral, the RPMs drop vs holding my foot on the brake in Drive. This could imply that less fuel is being used, but wouldn't if neutral actually provided more resistance. However, it certainly feels like the engine is under less load when in neutral as well. I haven't verified this using the OBD2 port, but could if I had reason to believe that piece of advice had any sort of sound backing.

OR ........
Do what I do:
screw all that, just resign yourself that these are not fuel miser cars, do what you can and limit your spirited driving to sometimes instead of all the time.

OP and other readers looking to increase economy: maybe it's too late for this vehicle, but seriously, look at the window sticker, look at fueleconomy.gov, look at the specifications, and don't by a vehicle that desires or requires higher-than-87 octane fuel if you can't reasonably anticipate being able to afford the fuel for as long as you may drive the vehicle. Taking action to get better mileage in whatever you drive isn't a terrible thing and can be a fun challenge, but being disappointed by a vehicle that consumes fuel pretty much like you should have expected it to is a waste of energy. That having been said, I'm sure there are plenty of sites that have all sorts of suggestions (some more common knowledge than others) on methods to save fuel, so search for them, but when you do, I highly recommend staying away from little gadgets that will allegedly pay for themselves. For instance: http://www.wisegeek.com/what-is-the-turbonator.htm

[Sstupid]

I get 14.5 MPG.

[pegasus]

I get 18 in the winter, 20+ in the warm weather, wonder if they change gasoline blends for different seasons?

[EdBwoy]

I get 18 in the winter, 20+ in the warm weather, wonder if they change gasoline blends for different seasons?

Yes they do, especially for areas that get "winter". I would need to break out the good book to see what the exact explanation is, but the gist of it is that winter gas is made to ignite easier (no effect to octane number though). In effect it has less energy per unit volume/mass which means you use more fuel to keep up the same performance in your car.

[DS2009m35x]

I'm in Ct and I agree with the comment regarding Winter and Summer blends. On relatively conservative driving (most of the time ) I get 19.5 MPG mixed driving with probably 2/3 highway. In the winter it decreases to about 18.5MPG. They do comment on the seasonal blends of gas on the radio as well. 2009 M35X.
Regarding MPG, I had the plugs replaced last year and did not notice any difference in MPG.