Just started happening a few months ago, but the speedo will hang on a specific speed and then 'jump' instantly to 3mph or so higher. For instance, when accelerating at a smooth steady pace it will sit on 50,50,50,50, then bam 53. It's kind of hard to explain, but completely obvious when you see it happening. It never used to do this. Any ideas?

Sorry, it's an '08 malibu classic with about 40k on it.

These aren't our old speedo's that are actually tied to anything. My suspicion is that the refresh rate is something like 2 seconds which is admittedly noticeable to some people. I havent noticed it on my '09 but I know that the speedometer is just getting a digital signal saying what speed the car is going however often it is set to ask.

I was able to reproduce something similar by setting my scangauge to slow updates, and accelerating. Rpm was like 2304.......... 2750........ 3500..... and so was the speed jumping 27 to 33, etc.

I would say, if you haven't dramatically resized your tire diameter and it isnt more than a 2 second interval and it also seems about right, it's probably normal. Do you have cruise? set it to "60" for 5 mile markers and make sure you're within 5 seconds or so...

These aren't our old speedo's that are actually tied to anything. My suspicion is that the refresh rate is something like 2 seconds which is admittedly noticeable to some people. I havent noticed it on my '09 but I know that the speedometer is just getting a digital signal saying what speed the car is going however often it is set to ask.

I was able to reproduce something similar by setting my scangauge to slow updates, and accelerating. Rpm was like 2304.......... 2750........ 3500..... and so was the speed jumping 27 to 33, etc.

I would say, if you haven't dramatically resized your tire diameter and it isnt more than a 2 second interval and it also seems about right, it's probably normal. Do you have cruise? set it to "60" for 5 mile markers and make sure you're within 5 seconds or so...

Thanks, I'm not terribly concerned about it, just a bit confused because it just started happening, and no tire diameter didn't change. I'll throw my GPS in and see how close the speed is, usually the GPS seems to be perfect so it's a good way to check.

Anyone else see this before? Just seems bizarre that it started happening out of the blue.

Have you plugged anything into the OBDII port recently? Like, ANYTHING... even an emissions test equip. That, or a new battery/battery service?

It is able to be controlled by the computer, the refresh rate, there is just no reason it would change randomly: do you agree? If it turns out to be accurate, and no other symptoms, it may be able to be reset back by a tuner if desired.