Does anyone know the highway crusing speed used to produce optimal mileage results with a Scion tC?

 

keep RPMs down, key factor

 

Probably 50...thats about right before you start the power band.
50-55
Maybe a little higher for autos.

 

^^ exactly. And even more important is to run at a steady speed and accellerate smoothly. When travelling to my home town I set the cruise at about 80 mph for about 90% of the 9.5 hour drive. I see between 28 - 32 mpg every time, including AC on, AC off, winter, summer, etc.

 

Is your tC Auto engifineer?

 

best speed to go is just around peak tq of the motor.

 

Mine is a 5 spd. I was saying exactly to the the post above the one I pointed to, the other guy posted in between.. so it made mine sound a bit confusing

 

i thought you were agreeing with mine
but was confused

 

I was... but managed to post slow and confuse everyone :D

 

ish happens
we got the jist of it

 

So let me give you a situation...

Auto, which is better for the MPG...

65-70 mph/ ~2500 rpm

or

80 mph/ ~3k rpm

?

I have 80 miles of hwy commute everyday and I would rather do the quicker option but if I got an extra 80 miles if I went ~65, I wouldn't mind doing it.

 

Obviously the slower speeds will be better for MPG.

TO really compare I guess you should fill up, do a trip at 80, and calculate the MPG, and repeat for the other speeds.

My guess would be the slower is better, but it won't make a ton of difference.

 

I try to keep it under 3k RPM when on long trips. In the city, I rarely use cruise control.

 

Depends if you have auto or manual.

On both, best to keep rpms low so I do about 70 on manual (still over 3000 rpm).

The auto is geared much better for highway cruising so I would go a lot faster on without worrying about mileage.

 

I haven't found there to be a big difference in fuel economy while on the highway at constant speed. I have the 5spd and have done the same trip at 65 and 80 and both times got 31.2mpg. Both times I had the AC on with about the same weather. I would estimate there that there is only about 1mpg at most to be saved by keeping a lower speed.

 

90+

 

what rpm doyou guys run at 70mph? im at 3100 w/ the sc... curious if mods change that...

 

only if your mods include changing out your gearing, or if your tire size is different from stock.

 

easy way to find out... get a ScanGuage II !

 

First part:

http://youtube.com/watch?v=URI80bckL...=Audi%20diesel

Second part:

http://youtube.com/watch?v=qmAK4OB9R...les%20part%202

You guys could learn a couple of tips to save on gas from this video.