Better Mileage Shifting Manually
 

Just as a data point, if I drive my 4.8i X5 in "D", I get a little over 18 mpg in complete highway driving. If I shift myself, I get 20-21 mpg. Admittedly, I shift BEFORE it gets to 2000 rpms. Yes, it somewhat defeats the purpose of getting the V8, but I am liking the fact that I am actually "beating" the advertized mpg. I usually drive 75-80mph on the highway.

Just thought I'd share my mpg experiences. :D

This is completely normal. Usually, the lower the rpm, the lower the fuel consumption.

I practically choke my dad's Mazda MX-5 because I drive it like I drove the 118i EfficientDynamics, upshifting at 2100rpm.

I went for quite a while using manual shift and I couldn't help but let the revs go higher before shifting. Feels completely like a different car - not to mention - it was entirely too tedious shifting it early and often.

BTW, is it completely safe to let the computer downshift when coming to stops everytime? I find it's doing a fine job of that anyway so I didn't bother, at all. I feel kind of guilty/reserved messing with manual shift though - new tranny and all. 5.5 months and still under 2k miles... but loving it everytime I'm out there.

Its perfectly fine to let the computer down shift. The one thing that I wish is that even though I don't have the sports package, I wish they still gave us the option of having the paddle shifters. This way, I can keep both hands on the wheel...

Let me get this right, so if you shift before the engine hits 2000 rpms you save gas? Of course you do, you are accelerating at the speed of a small child. You'd get the same out of "D" if you placed your foot on the pedal as if it were made of glass. :)

That advertised mileage is based on average acceleration and speed, not tortoise like acceleration and then simply sitting in overdrive and 6th gear.

But yeah, you probably would get much better gas mileage. :)

I drove 75-80-85 through a section of NC interstate and got 19.1 mpg yesterday in my 4.8. And I am just as 2K miles using D, no manual shifting for that stretch.

Real world mileage for me in a 3.0si is just 15.0mpg according to my trip meter (no manual shift). This is 80% local roads. On these local roads for many weeks, I was about 14.8 then it went up to 15.2 after only a couple short highway runs. Hoping real-world will eventually make it to 16-17, but right now I'm laboring to get there. 2k miles, don't think I'm really in break-in anymore... and not all that heavy a foot either.

I am getting 19.3 on my 3.0si, and I don't have a light foot either. I have 11,000 miles on mine though. I recall hitting 19 mpg around 5,000 miles or so. I find that mpg improves dramatically the more you drive it. :thumbup:

By the way, almost 6 months and ONLY 2,000 miles. You have to get out more. ;)

You're telling me.. I've been working from home for years now - I can't even remember which year it's been so long.

I can't wait for the day I see 19 on that screen. ;)

I took a long trip last week and put in 1300 miles. Fully loaded with my family plus full of bags. I averaged around 23 mpg on my X5 3.0. I did notice that when the speed was about 75 mph, mpg was around 21. But, when I drove slower around 65 mph, mgs was around 23-24.

Last time I checked, my friend had only put like, 1600mi after 6 months. His parents barely drive it to work due to the fuel consumption. 12 miles to the gallon in the city is not funny.

it's worse in the winter months due to allegedly added antifreeze type additives in gasoline during winter time also with heated seats, defrosting AC compressor etc...

Anyway, I;m happy with the 4.8i especially doing highway. i can almost get it to go 700 km. Almost 28 imperial MPG

Maybe I'm missing something, but how does manually shifting affect your highway mileage? Speed would be the bigger factor, as you should be in top gear all the time (assuming it's not a very hilly area).

FWIW, I get 15-16 in mixed/mostly city driving and 18 (80+mph) - 21 (~65mph) on the highway. Pretty much EPA numbers.

Vehicle now has 8,500 miles on odometer.

While on the highway, the car downshifts while you are passing. When you get to a toll booth, you do some stop and go's. I was surprised to see how much this mattered. When you go on slight uphills, it also downshifts. When you shift yourself, you have control over whether or not you want to downshift out of 6th gear.

No, technically speed is NOT the biggest factor in determining mpg while "cruising" on a flat highway. It's drag coefficient and weight. It's RPM (i.e. - how fast your engine is spinning, and therefore, consuming gas) and any acceleration. If you keep both on the low end; i.e. - slow acceleration while keeping RPM's low, you would get the best mileage.

OK, I thought when you said "highway" you meant relatively flat Intertate w/o significant traffic, and no toll booths etc. that required you to stop.

As to your second point, since the other factors you mention (drag coefficient, weight) are basically fixed, then speed IS the one variable that makes a difference in mileage. (you also mention RPMs, but it should be a given that you're not cruising highway speeds in less than top gear) In fact, aerodynamic drag increases at a rate equal to the square of velocity (i.e. a 20% increase in speed means a 44% increase in drag). So speed is a mileage killer......unless you're on the moon.:D

Ok, so I guess we will be "geeking out" here. With drag coeff being constant, if you're travelling at 70 mph and driving the engine at 2000 rpms (roughly) at 5th gear OR you're travelling at 70 mph at 1500 rpms (or so) at 6th gear, at which gear would you be burning more gas? Answer is 5th gear since the rpm is higher. It has nothing to do with the speed.

Well, Armand, I guess you're right. Yes, if one is stupid enough to purposely drive around at 70mph in 5th gear, he'll get worse mileage than if he drove in 6th gear.

Someone call CNN and inform them of Armand's scientific breakthrough!!!

Hey, I just thought of another one: Driving w/o the parking brake engaged improves highway mileage (speed being constant, of course).

Energy crisis - SOLVED!

:stickpoke (just kidding with you, man!)

It also downshifts if you are going down a long hill or grade on an interstate. I use manual in this case to keep it in 6th.