xB MPG Range?

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Aug 9, 2007 | 05:58 PM

#41

dz302

Senior Member

SL Member

Joined: Aug 2007

Posts: 551

From: Aiken, SC

Re: Xb MPG Range

I have had my xB for almost 1.5 years. I bought it new and have religiously checked MPG.

Back and forth to work - 80% city, 20% highway: consistent 31-32 mpg
Interstate travel @ 70mph steady: 34-35 mpg
Interstate travel @ 80 steady: 32-33 mpg
Highway travel mostly 55-60 mph: 37-38 mpg

I drive very conservatively, keep tires properly inflated, no jack rabbit starts.

Aug 9, 2007 | 06:53 PM

#42

BoxOffice

Senior Member

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Joined: Dec 2006

Posts: 1,031

From: Silver Surfer

Re: My mpg seems too low

Quote:

Originally Posted by jasonsxb

I just got my beautiful blue '06 xb a month ago (it had 15k miles and its an automatic) and I've filled the tank 3 times (after the light goes on and I don't top off the tank):
1st fill - 9.5 gallons, 220 miles
2nd fill - 9.3 gallons, 200 miles
3rd fill - 9.4 gallons, 210 miles.
Each time using 87 octane at Mobil.
That averages out to only a little over 22mpg. Most of my driving is in the city, and when I am on the freeway there is usually stop and go traffic. (Its Los Angeles - what you gonna do?) So, what am I doing wrong? The only significant mod I've done is new wheels (18" chrome, so sweet), so tire pressure isn't an issue. And I drive insanely conservatively. (For example, I live on very slow street and I'll often kill the engine at 30mph 6 blocks from my house and try to time the coasting so that I stop in my driveway without hitting the brakes - I actually did it perfect once)

Any thoughts...

Wellll...I commute in/to L.A., too, and I average about 33-35 (without trying). My best is 43.6 mpg, 486 miles, commuting (trying hard). Just for comparison, my worst tank was a 30.0mpg with constant use of A/C, and all city driving.
I hate to say it, but those 18s are part of what's killing your mileage - as much the added weight of the wheel as the wider, stickier rubber of the new tires creating extra drag.
Other than that, read these:
https://www.scionlife.com/forums/viewtopic.php?t=166146
https://www.scionlife.com/forums/viewtopic.php?t=165660

There are some other good posts, too, just run a search.
Good luck!

Aug 9, 2007 | 07:06 PM

#43

BoxOffice

Senior Member

SL Member

Joined: Dec 2006

Posts: 1,031

From: Silver Surfer

Quote:

Originally Posted by Kerry

Hi tkanaz,

Re: "I have 205 50 16's. That's the only difference." From your reply it appears you don't think the size differences account for your poor MPG. I know nothing about these things so this subject is of interest—eventually I'll have to replace mine, it would be nice to know the effects of diameter on MPG.

You've changed two size aspects from the OEM P185/60R15 size tire. Do the "60R" and "50" measurments refer to the width of the tire's footprint? If so, it would seem that your narrower tire would cause less resistance than my stock width of 60R
Kerry

No, they refer to the "aspect ratio" of the tire, meaning that on the "60" series (the "R" just means radial) tire, the sidewall is 60% as tall as the tire is wide, and therefore, with the "50", the sidewall is 50% of the tire width. In other words, on a P185/60-15 tire, the tire is: 185mm wide, and at an aspect ratio of 60, the sidewall is about 110mm tall (185 x .60 = 110). The lower the aspect ratio number, the shorter or "lower profile" the tire. The "P" just means it's meant to be used on a passenger ("car") type vehicle.
Obviously, the "15" refers to the diameter of the wheel the tire fits on.
Your guess that a narrower tire would cause less rolling resistance, however, is usually true, especially combined with the fact that most wider/lower profile tires are performance minded, and utilize "stickier" rubber for better handling, which do not roll as easily as harder, "stock" tires, particularly in the case of a cheaper, economy-type car like a Scion.
Hope that helps!