i have 16.5k on mine and i drive 75miles each way to work and if i stay right around 3ooo rpm like 79, 80 mph i avg 27mpg, but i dont i do between 80 and 90ish, i get 25mpg rock solid, if going to and fro work wasnt such a boring ride i would take it eaiser but it shaved a good deal of driving time going faster + it keeps me awake driving like i stole it ..lol

 

I'm getting consistent 25-27 MPG in all city driving doing my own division calculations at fill up. When I pull a long highway trip, I easily see 31-32+. I'm not hard on the throttle though.

 

guess many of you would really be complaining if you were getting the mpg i am
18.9

that is not a typo -- i'll post the pic shortly
it is a mix of 40 city, 60 hwy

i have never had higher than 26.9mpg
that was traveling to NY -- all highway

 

Mines been around 24 mpg lately mixed. When I first got it, it was a little over 27 mpg. I'm wondering if the winter blend gas is the reason for it (and my heavy foot LOL)

 

I bought mi new 08 XB and on the wat home I set cruze at 55 mph and got 26 mpg. I have little over 1000 miles and got 27.6 mpg on freewy at avg. 74 miles per hour. I noticed taking it easy in town I get 24-25 mpg. I have stayed on 25 mpg since I installed my 20" wheels. Good luck all....

 

Winter blend lowers the mileage (about 20% less BTUs) and the colder air makes more drag as well as everything is colder in the transmission and bearings causing more drag. Check your tire pressure as it will drop when the tires get cold and they usually leak a few pounds every month. Sitting at a light when the engine is warming up will really burn a lot of gas and lower your mileage for the next 5-10 miles. Make a few short trips and you can kiss the mileage for that tank goodby. Engine break in takes a while so don't expect great mileage until you get a few thousand miles on it.

 

This may have been mentioned before. If it has been mentioned, this may illustrate it differently from how others have described it.

Driving economically is not about accelerating slowly, it's about preserving momentum with the least amont braking that is safely possible.
The most economic acceleration occurs at about the maximum torque rpm (4000rpm in the xB). This means driving economically is accompanied by decent acceleration rates. This means if you have a clear road ahead with no red traffic lights enjoy the fun of good acceleration rates while achieving the best economy possible.

Now hears the least fun part, to achive maximum economy approaching a stop sign or stop light, take your foot of the accelerator early enough so that the momentum left in the car will have you just about stopped when reaching the stop without having to touch the brakes. Word of caution this drive most other drivers nuts. For a red light these other less knowledgeable driver cannot understand that there is nothing to be gained (and much to be lost [gas]) by maintaining your speed up to a red light and then coming to a quick stop.
Now when I see that light turn green, I am instantly back up to 4000 rpm with my back pushed into my seatback. e.g. if I'm travelling 50mph, and I see a red up ahead I immedialtey start coasting and if I'm down to say 40mph when the light turns green, I immediately have the rpms back upto 4000rpm to get up to 50mph briskly. Most people don't have the patients for this technique, even though for a stop light, it doesn't add any time to your drive, as you punch it the instant you see green.

Now for approaching stop sign it will add to the driving time as you may have to take the foot off the gas a half mile before, say at 50 mph, so this is where you have to decide between economy or getting quickly from A to B.

What drives me nuts is people who falsely believe they are achieving good economy by accelerating extremely slowly with no consideration given to economincal braking techniques, in the belief they are achieving better economy. The mpg display in the xB2 and other cars may also reinforce this false belief as the driver sees their instantaneous mpg jump to >99mpg when they are braking. It's difficult to explain this last point to your average Joe.

 

Only one thing to add and that is with the VVTi hard acceleration is not as efficient as moderate acceleration. Seems to work best in the brisk throttle range which is maybe 1/3 throttle with good revs and not flooring it which can waste some of the power due to valve timing changes and plug misfires. If you feel the engine bog down as you press down the gas pedal then you went too far. Also remember that with your foot off the gas and the engine slowing you down you burn zero fuel since the injectors are cut off so unless you are going really fast 30+mph it is better to keep it in gear than to coast in neutral since it takes some small amount of fuel to coast and keep the engine running at idle usually 0.2-0.1gph. I usually do the half way decelerate between stop signs - brisk acceleration and then hold speed until the half way point then engine brake in 5th down to 20mph as I reach the next stop sign.

 

Hahaha I'm sorry, but that makes no sense. On a brand new 2008 xB2 you're telling me that your car misfires already?

Also you're saying that the fuel injectors are completely shut off when you release the throttle?

Hahaha - if it were shut off, your car wouldn't be running. Fuel injected cars have IACV valves that control your idle, obviously when you idle you must need fuel or else your engine would not run.




Sorry to bust your bubble, but your previous statement made no sense.






Back on topic, I'm currently still on my first tank, I'm at 1/4 now and I've traveled about 230 miles. I'm sure mileage will get better as the engine breaks in. I'm currently shifting at 3500 rpms to ensure that I'm in the powerband.

 

I found this information on a website:

Getting into the highest gear you can, at the lowest possible speed, will save you plenty of gas.

Why? Because you use less gas when the engine is turning slowly. The slower the engine turns, the fewer the number of explosions in the cylinders. And fewer explosions means less gas consumed.

So, if you drive a manual transmission car, shift sooner. As long as the engine doesn't buck, shudder, or ping, you're fine. You'll sacrifice the ability to accelerate quickly — but you can always downshift if you need to accelerate.

http://ask.metafilter.com/63020/How-...ut-of-a-5speed


Is this true? And is it safe you use it if you have a auto XB2.

 

That's not true at all. When you're in a high gear at low speeds, your engine is bogging since it is NOT in it's powerband. Therefore when you try to speed up even EVER SO SLIGHTLY you burn MASSIVE amounts of gasoline in order to reach the speed you desire.

HOWEVER when you're IN your car's powerband. You use very little fuel in order to maintain as well as accelerate. It's not how much you can bog your car. It's how little throttle you can use to maintain your speed that determines your gas mileage.

 

Yeah plug misfires like when the engine is cold and you hit the gas too quick it dies - never happen to you HUH? Well it usually doesn't happen at high RPMs but it can - you just don't notice it as much.

You should look at what the fuel consumption is at 4k rpm no load and then tell me that burning a gallon an hour is efficient - you have a few measurements to make before you start telling people how an engine burns gas.

Low RPM full throttle will only inject the proper amount of gas for the amount of air entering the engine not MASSIVE amounts - again you need to actually measure it before you make these statements - typical amount at 1000 rpm would be about 1.8-2GPH or less at full throttle.

 

Haha, the only real-world proof is through a gas-mileage competition through driving at each of the 2 RPM ranges through the entire tank either in the same car twice or through 2 identical stock xB's.

 

WHAT? I just measured it on my ScanGauge at 4K rpm it was burning 1.1gph with the clutch held down and up a hill at a little over 1000 rpm full throttle only 1.2gph and I couldn't hold it at full throttle too long because it picked up too much speed.

 

I agree with MaxBoost925 about not accelerating using high gears at low rpm to save fuel. High gear at low rpm is good once cruising speed is reached. What counts is the work produced per second for a given amount of fuel. Put it another way.
If Driver 1 is accelerating and shifting up early to keep the engine rpms low, it might take say 45 seconds to get to 60mph. So even though the average amount of fuel being consumed per second is lower, it was being consumed at that rate for 45 seconds. Where as Driver 2 upshifting at the maximum torque range might get to 60mph in say 15 seconds. Driver 2 may have used fuel at twice the average rate of Driver 1, but they got up to 60mph in a third of the time. i.e. the fuel was being used more efficiently.

Example:
Driver1: .001 gal/sec * 45 sec = .045 gal to get to 60 mph
Driver2: .002 gal/sec * 15 sec = .030 gal to get to 60 mph

When cruising at 60mph both would then consume about .0005 gal/sec or 1.8 gal/hr (approx 33mpg).

If this was the actual scenario Driver 1 would have burned 50% more fuel then Driver 2 to get to 60 mph.

Also Driver 2 is achieving maximum economy in top gear 15 seconds after he started.
However, Driver 1 is achieving maximum economy in top gear 45 seconds after he started.

So Driver 2 is achieving maximum economy for 30 seconds before Driver 1 starts achieving max economy.
Driver 2 also had the benefit of reducing his journey time.

It would be interesting to know optimum % throttle opening with respect to the rpm that give the most effiency. This should be accompanied by pretty satisfactory acceleration rates too.
e.g.
30% open at 2000 rpm
25% open at 3000 rpm
40% open at 4000 rpm
35% open at 4500 rpm

I know "flooring it" does not give good efficienty rate due to fuel enrichment due to less homegeneosity of the air fuel mixture.

 

I drive with a lead foot and I have never dropped below 22.8 MPG.

 

DUDE! I drove from Tiverton to Newport today and got 46mpg and came back before the engine cooled off and got 53mpg.
From what I have measured going up hills in various gears at the same speed - the best MPG is obtained in the highest gear that can get you up the hill. Using a lower gear with more RPM burns more gas yielding lower MPG.

 

my dealership said there is no break in period any more, so no special driving rules apply anymore on the first X amount of miles.

 

And as we all know, the dealer knows best.

 

ha ha ha ha ha yeah absolutely - the breakin of an engine rings is already done when they first start it up and they do drive it off the truck that transported it to the dealer. But all the metal parts inside the engine that rub against each other usually protected by a thin film of oil do need to get polished and the one very important surface is the cylinder bores for each piston. That takes a lot of strokes and if you happen to do a few perhaps even ONE really hard acceleration and overheat the surface reducing the oil film that is there you can change the seal of the piston rings from that point forward and never get them to polish properly to give you the best mileage. There are also rollers on the cam chain, valve stems and lifters all needing a little polishing as well. There are all the gears in the transmission also. This is part of the reason why the engine warms up quickly when new and takes a lot longer after it is broken in.