Why is it no matter how fast I go it always says like 25-37 etc..I was just doing 80 on the highway and it says 37..

 

I believe it is an average of your speed in between resets, try resetting it and see what happens. I mostly drive in town and my average speed is like 28 or so it says, if I reset and go on a trip it is higher.

 

That is the average that it has registered overall. I reset mine every time I get gas. Mine usually says about 30, When I took a trip and drove all day at 65-80 mpg then it showed over 60 since it took into account the slower speeds when I hit traffic problems or pulled off the intestate to grab lunch and I was going 25-35 mpg in those towns.

 

I have reset, but I will again next time I get on the interstate...thanks all

 

Let's see: if you drive for 1/2 hour at 30 mph you have gone 15 miles. If you drive the next half hour at 60 mph, you have gone 30 miles. So, you drove 45 miles in that hour. Therefore, the average "speed" is 45 mph.
Not exactly important information, but it could figure in one's reasoning somehow.

 

That is correct if you reset it once cruising. But if from a standstill, it will count each MPH as you speed up/slow down.

 

If one HHR leaves Boston at 1:45pm traveling South at an average speed 65mph and another HHR leaves L.A. at 3:20am traveling East at an average speed of 85mph, at what point should the HHRs............

You need to realize it is hard to make up for going 5mph or 10mph in your drive way or down your street and 0MPH at every stop. While driving reset the display and then it shows you a fair reading.