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Discussion Starter · #1 ·
I know this has been discussed over and over in this forum but I still cannot explain why my 2010 XB's mpg is only around 17-18 mpg. So here are the details:

I live in Los Angeles
XB has 17" Scion 10 spoke Wheels
TRD exhaust
I use 87 octane gas from Costco
Just changed the spark plugs
Just changed the oil from regular to synthetic mobil 1
Had a trd cai but just put the stock back on
Driving habits are normal...no racing or anything like that


I'm thinking of changing over to 91 octane.....


Any ideas anyone.... I use the miles driven divided by gallons filled to get the 17 mpg
 

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Can you give us a little information on what type of traffic you drive in since LA sometimes looks like it's bumper to bumper and not much traffic moving.

A/C on or off? How far your daily drive is? Freeway or city?

91 octane I believe will not help.
 

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Discussion Starter · #3 ·
Its mostly local street traffic with the normal (for LA) traffic lights and stop signs. I don't depend on the gauges bec they are not accurate. I've never gotten the 22 mpg city stated for this vehicle. Daily mileage driven would be an average of 25 miles. I don't drive with the a/c on.

Also, why is it that the "miles remaining" gauge does not reset after I top off the gas thank?
 

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Stop and go traffic really lowers mpg. It's all about how heavy your foot is. Do you do jack rabbit launches at traffic lights?
 

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A/C on or off has been proven not to matter. What matters is what year your toaster is. If it is a 2008-09 then you might want to see about getting your ignition coils replaced (they were recalled) But also, look at getting seafoam. I hear that is the best stuff for improving your MPG. But also, having an inch higher rim does make a difference too (small but a difference) because the larger the wheel, the more power it takes to turn it. Also the type of oil you use in your engine (doesn't seem legit, but trust me, it makes a difference) Try using synthetic oil over conventional.
 

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One more thing to think about is-how much stuff do you carry with you? If you carry a lot weight, your mileage would go down.
 

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Discussion Starter · #7 ·
Pretty sure the overall diameter of the 17's vs the 16's was the same. The 16's had a higher profile tire while the 17's had a lower profile tire. I don't drive with a lead foot but there is some stop ang go traffic but enough to justify the difference between actual 17 mpg and claimed 22 mpg city.
 

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When I had to 19s I was avg around 18mpg and it would make me so angry. Now I'm avg around 23 with mainly city driving. Short bursts to get to the other side of town on the freeway and stop and go. Freeway I get around 29-30.
 

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A significance for rims/wheels in short-burst driving (like in cities) is the unsprung weight difference. Heavier tire/rim combos take more effort to get moving and to stop moving. That is why rims changes affect performance and MPG.
In this case lighter is better . . .
 

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A significance for rims/wheels in short-burst driving (like in cities) is the unsprung weight difference. Heavier tire/rim combos take more effort to get moving and to stop moving. That is why rims changes affect performance and MPG.
In this case lighter is better . . .
exactly, i also loved the steering response with the steelie 16"s and the added mileage.
 

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"miles remaining till empty" I never use this or pay attention to it. Are you resetting the MPG part of the guage when filling up? I would think that would have to be done for the other part to give you a some sort of reading that matters.

Good advice given here, how about the air pressure in the tires? Sometimes it's the little things.
 

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"miles remaining till empty" I never use this or pay attention to it. Are you resetting the MPG part of the guage when filling up? I would think that would have to be done for the other part to give you a some sort of reading that matters.

Good advice given here, how about the air pressure in the tires? Sometimes it's the little things.
i keep mine at 35psi, its a little soft but my sidewalls are hard. Ride Quality > 1-3 mpgs
 

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Discussion Starter · #13 ·
By what everyones posted so far, seems like the wheel size change from stock to 17's could be the culprit. Tire pressure is maintained at normal levels for that tire size. Hard to believe that the weight difference between the Toyota 10-spoke wheels and steelies is enough to warrant a 5-6 mpg difference.

Although, one thing I have not done since lowering the xb with eibach pro kit springs is align the xb.
 

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2011 Scion xB Release Series 8.0 SoundWave
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I just did 360 miles on a tank with 95% hwy and 5% city. I only got over 90 mph twice to break some idiot off or two. I also did a 55 mile test at 60-65 mph and averaged 36.5 mile per gallon. This is an automatic folks, not a stick. I don't need a stick, that are out dated in my world.
 

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I think the only reason I would want an auto vs a 5speed is if I drove on the interest every day. Otherwise, I prefer them. But I wouldn't rule it to be JUST the rims. Other factors could play some role. Try Seafoaming your car, using amsoil synthetic oil, etc. Things that I've mentioned as well as others.
 

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I think the only reason I would want an auto vs a 5speed is if I drove on the interest every day. Otherwise, I prefer them. But I wouldn't rule it to be JUST the rims. Other factors could play some role. Try Seafoaming your car, using amsoil synthetic oil, etc. Things that I've mentioned as well as others.
I would not make it more complicated than it seems. Rims make a huge change in MPG. Seafoaming a 2 year old modern car will do NOTHING. Seafoam does not give better mileage unless you have an old neglected car that has build-up on the injectors and rings/valves. With the amount of detergents in today's gas that buildup is nowhere near what it used to be in old carbureted cars... Do not waste your $$ on snakeoil and hearsay.
It is proven that the added unsprung weight of oversized alloy wheels will decrease mileage mostly in stop and go. But you can also coast longer on heavier wheels than you can on light ones depending on how you work the gears...
The other thing is I would manually calculate the milage. I have found that the in car avg. milage takes into account stop/idle time. Averaging many 0's/mpg into the equation. You can see this also by the average MPH that it also shows. I highly doubt my average cruzing speed is around 17mph (like it always says) when the speed limits here are at the lowest 25mph... and I go over that more times than not especially on the freeway for 20 miles.... I use an obdII port bluetooth device and an android app (torque app) to get a better more realistic avg. Or just do it by hard math. My in town rush hr. avg is 18.6 up from (15-17 after a few mods) with the TRD 19" wheels. The car says 17.
Also dont believe the gauge if you have reset the battery because it takes time to relearn the fuel trims and will give you wild numbers.
 

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Oh man... I missed that you didnt do an alignment after lowering... That is your problem right there. You are adding friction between the wheels and the road, wearing your tires twice as fast and killing mileage. :cheers:
 

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By what everyones posted so far, seems like the wheel size change from stock to 17's could be the culprit. Tire pressure is maintained at normal levels for that tire size. Hard to believe that the weight difference between the Toyota 10-spoke wheels and steelies is enough to warrant a 5-6 mpg difference.

Although, one thing I have not done since lowering the xb with eibach pro kit springs is align the xb.
Guess I don't understand why anyone would be willing pay for lowering springs and not be willing to pay for an alignment after install. Lowering the vehicle changes the toe, guaranteed. Changing the toe without re-alignment results in scrubbing rubber, guaranteed. I installed ProKit on my xB2 and guess what, it threw out the toe! Is anyone surprised?
 

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"miles remaining till empty" I never use this or pay attention to it. Are you resetting the MPG part of the guage when filling up? I would think that would have to be done for the other part to give you a some sort of reading that matters.

Good advice given here, how about the air pressure in the tires? Sometimes it's the little things.
"Miles till empty" hits zero when the light comes on. The tank will still have 3.5-4 gallons (forgot exact trigger level) left of it's 14 gallon capacity.
 
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