I have a 2010 RX and the average MPH is constantly at 16. I'm talking about miles per hour, not miles per gallon.

I don't think I've ever driven 16 mph in my life. Why is this happening and is there a way I can reset it or does it have to be done by Lexus?

 

Mine is at 24 MPH. Remember that this calculates idling time at stop lights into the equation. Not sure if you can reset it. I know you can reset your overall MPG.

 

As far as resetting the MPG, is it true that it's done by resetting the trip odometer at the time of filling up the gas tank?

 

There are 2 different MPG's. Overall and after last fill up. Mine automatically resets when I fill the tank. However I do reset the trip meter at each fill up too. I have always verified the MPG the car says I'm getting and what I actually am getting, and it is dead on. I do let it run down and I completely fill the tank each time. I don't add $10 or $20 at a time.

I am filling up today, I will pay attention to whether the trip meter resets it or it does it automatically.

 

Well, it seems it resets when you reset the trip meter. Takes care of that.
I believe you can reset your overall mpg too.

 

Getting back to the miles per hour question, does anyone know how that resets? Mine is also very low, so it is almost useless to me since those zero miles per hour hit the average so hard.

 

When the MPH is displayed, if you push in on the selector switch, it will reset it.

 

Thanks for the info

 

Well, looks like I was wrong. When I filled up last week I didn't reset the trip meter. Once I moved forward the MPG's for 'since last fill up' reset. Amazing.

 

There will be all kinds of variables from temps, hills, traffic lights, to your style of driving. I live in an area of hills and short distances between lights. In the winter when temps were cooler I was down to as low as 28 overall. Now that it's warmed up, much better. Of course mine is an (h) but there are still differences between seasons all other variables being the same. Even Octane will make a difference. Lots of comments here about that but for me, Shell mid-grade 89 octane seems best for me. The 93 is actually less performance and mileage for me.

See link, I recently experienced my best yet. https://www.clublexus.com/forums/5395684-post10.html