thepixi

____. I didn't even realize this was the 2nd gen thread...I just searched "XB mpg" and it came up.

Anyway, I'm disappointed to know about the defrost/ac compressor connection. Wonder if I'd get better mileage with it NOT on defrost setting...then again, I always did that in my 05 XA and got 37mpg on avg. WTF?

JMS5000

Oh, no - not at all. Actually, I hadn't even considered gender in my response. As a matter of fact, any auto repair tech that takes advantage of anyone like that is an abomination. Absolutely despicable.

I brought it up because in my old Camry, i' had three ***** and an AC on/off button, and if that button wasn't pushed - no compressor - no matter where the air direction **** was set. Yet in my Suburban, the defrost setting engages the compressor automatically. Definitely not ISO 9001:2000 compliant.

Oh, and I guess back on topic - Had my RS5 for about 3 weeks and 2000 miles now, and I'm getting about 28-30 MPG on 90% highway at about 60-65mph. Yes, people go around me a lot!

thepixi

Well you know, this is the whole reason I signed up for an acct here...I know very little about cars in comparison to most of the ppl here, so I depend on you guys for advice.

In case you hadn't noticed, I'm in an 05 XB (I just searched the words XB mpg and this thread came up, I didn't even realize it was a 2nd gen thread).

Anyway, I'm still thinking something may be wrong with my car. I bought it from Carmax (I know I know, but they were the only ones that would approve me for the loan, and no one else had used XB's...plus the 'no haggle' aspect is nice). It occurred to me that when I sold them my XA they didn't even bother to ask if the 30k maintenance had been done on it (which it hadn't). I got the XB with about 32k miles on it and just assumed the maintenance would've been done by Carmax if needed...wrong. My car lagged a lot, so I checked the spark plugs and they were all burnt and looked like hell. It has a little more power since I changed them, but I still can't get over this gas mileage issue. Is there anything else that could be causing it? (I had a faulty gas cap replaced as well). The VERY BEST mileage I've gotten is 26mpg, and that's with putting in neutral at every stop, accelerating slowly, all the 'gas saving' tricks everyone talks about.

xActly

One of the first things you should try is cleaning the MAF sensor...they did that for me at the dealership when I had it (the xA) in for something else and the mpg went up from 27-28 to 31 the very next tank (I drive it hard). A dirty MAF will kill your mileage because it monitors how much air is getting to your engine - false readings seem to always result in the computer sending more fuel, making your car run rich & gulping gas.

Get some CRC QD Electronic cleaner

and spray the crap out of the MAF sensor element. It's inside the plastic air cleaner box, just at the exit where the rubber intake hose connects. It looks like a resistor or a tiny capacitor. Just spray it & let it dry...don't touch!

thepixi

Thanks! I'll be sure to let you know my results.

xActly

Update/bump - just filled up & calculated my best mileage yet: 25.3.

It's the first tank on my first oil change: Mobil1 0w20/Purolator PureOne filter.

The last 1/3 of the tank had a tire pressure advantage - all were 4psi low. Yet another reason Balise Toyota/Scion of West Springfield, MA sucks the big one.

Also, I've switched to 93 octane, and actually notice a performance difference at 4200ish rpm (VERY noticeable at 1/2 - 3/4 throttle). Maybe someone can confirm, but it seems as though the vvti does something with the timing/valving at that rpm. I didn't notice it nearly as much on 87 octane, which makes sense if it's advancing the timing...advanced timing can easily cause detonation with lower octane fuel, even in a low compression motor (which ours is not) and if that happens the ecu would retard the timing, which would kill the added power (all of this happening within milliseconds). Maybe I wouldn't see as much a difference if they weren't forcing the 10% ethanol blend garbage down our throats. Whatever. Anyway, for the extra $2/tank it costs to use 93, and the way I drive my cars, and the benefits I've seen with both of them, I'm sticking with it.

Anxious to see what my next tank is, considering the whole thing will be on properly inflated tires. Maybe I'll even try driving like a normal person. :D

xActly

Impressed so far...about 1/4 thru & computer mpg is hovering between 30.6 & 31.0. Usually 1mpg less than displayed, so if that's true, looking like 29-30 driving reasonably. Better than I got in my 2005.

danos_XBox

It's the color of our cars CSM is best.

Hey this is related:
I got my car back from installing the Tanabe NF210 lowering spring. Now I'll swear that my milage has to have gone up or something is really playing with my head.
Before my average computer display mileage was about 30 mpg generally. Now in the same places on the roads my average hovers around 45-55. This is not the real computed total MPG but, the varying one. I have to fill up fully and get real stats though>

xActly

Lower = more aerodynamic, I think. Even in a box.

spring

For all you folks saying you don't use the A/C and that is affecting fuel mileage......you need to know it is MORE fuel efficient to run the A/C than to have the windows rolled down.

My MPG is about 25-26, but if I really put some effort into driving efficiently, I can get about 28.

JMS5000

This is true, at highway speeds. At city street speeds, some car magazine said it's a wash. In other words, do what feels good. You only live once!

I gassed up the other day, reset the AVG, and hit the highway. I looked at it about 15 miles down the road and it read 39.4. I about fell out. I'm getting computer readings of 30.5 or so, and real life about 29.5. I'm reasonably happy. (Still want a bigger tank though).

spring

It also depends on the aerodynamic characteristics of the vehicle. Each vehicle gets slightly different results, but generally it is better to run the A/C for fuel milage.

Although, if you like the feel of driving in an oven, you can not run the A/C and keep the windows rolled up for max milage!!

thepixi

Someone please explain where I can get these 'computer readings' everyone is talking about.

CIONIDE

iTrader: (1)

Rather than trying to explain everything the multi-information display is and does in words, please see pages 140-142 in your owners manual. It will tell you everything you want to know, and how to do it.

Enjoy!

spring

Just press the left of the two button thingies on the dash guage cluster till it reads "AVG MPG."

Just experiment a little, you'll get it.

xActly

Yeah...we're already pushing some serious air at highway speeds with these bricks. Not sure how much worse it could be with the windows down. Still, probably better to stick to a/c on the highway.

But it's absolutely more efficient to run with the windows down & a/c OFF at speeds under 45ish (city speeds). The a/c pump takes what it takes regardless of speed, but it's hard to argue aerodynamics when air speed is so low.

To add another element of variability - it depends on how much power the car has in reserve. An a/c pump doesn't take the same percentage of every engine's hp - it takes a static number (around 10). 10 hp taken from our motors is about 6.5%...10hp taken from the first gen is 10%. Therefore, running the a/c will have a greater impact on mileage in the first gen than it will in ours.

10hp from a 2008 Vette is 2.3%...probably won't see a big difference there.

CIONIDE

iTrader: (1)

Vette owners probably aren't all that concerned with MPG ratings.

xActly

Surely not

xActly

29.65 mpg driving like a normal person (as opposed to speed racer, like I usually drive).

Sweet.

monkeydonot

Commute 80+miles daily, mostly freeway. There is a HUGE difference b/w heavy and light speeds. 75-80+ I get 28-29 mpg. 65-75, I get 32-34 mpg. Normally though, since I'm 90% freeway, I get around 30mpg @ 72-75. Had the car for 4500 miles. Hopefully, it'll get a little better. Haven't noticed any difference w/ TRD springs or synthetic oil.