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High RPM at highway speeds

i have a 2004 Mitsubishi lancer es 2.0 engine, and it’s an automatic. I seem to consistently get a little under 23 mpg no matter how i drive. I’ve noticed that when going down the highway at 65 mph, it is at like 2900 RPM, is this normal? We also own a 2010 toyota corolla 1.8 auto and it only revs like 2400, and a 2005 xB that revs the same as the corolla, i’m just confused that with a bigger engine, it would rev so much higher.

the xB is only a 1.5 by the way

It is all based on the transmission ratio. Does the lancer have an overdrive tranny? The overdrive may not be working. How many miles on the tranny and when was the filter and oil changed last.

There is 155,000 on the car, i don’t think the transmission has ever been changed, I’m also not sure if it an overdrive, i cannot find any info. As far as fluid/filter i also don’t know that either, it’s an 04 with tons of miles and it drives like a new car, i’m not the first owner, but i would imagine since it drives like a new car it was well taken care of,

I read something about “lockup” which that could be an issue, but, again, i don’t know how to check that out.

Well, overdrive amounts to a fourth gear in that car (probably). And you should be able to tell if it has a fourth gear. Listen and feel for the shifts, to 2nd, to 3rd, and then to 4th. It should also have a “lock-up” converter which feels like another shift, like 5th gear.

I might start with basic maintenance. Like a transmission filter and fluid change. If you do not remember doing this then you should do so. The rpms may be fine but how is your fuel use? How do you drive? Lots of stop and go or a nice easy with few traffic lights?