Well, I designed an Excel sheet that converts mph into Character and Chase scale speeds, and the latter into mph, and some of the speeds are dead on while many are off.
As an example, the Black Hawk is listed with a speed of 325 (32), which translates into 185 mph. I've checked several sources, including the DoD, and they all place it below that, ranging from 178 mph [310 (31)] to 145 mph [260 (26)], depending upon the conditions. Now, taking for granted that multiple sources should have been checked for these and a result drawn by comparisons between these sources, we can see that the 185 mph is too high.
The M113A1 is listed at 62 (6), or 35 mph. The sources I've checked place the Gavin, in any of its many configurations, as ranging from 37 mph [70 (7)] to 41 mph [71 (7)].
I won't even get into the discrepancies with civilian vehicles, most of which are far off with both company and independently rated specs.
The differences in figures may seem inconsequential at first, but when one considers that these distances are going to be measured during combat, including during chases, the errors begin to have a large effect on game play.
The problem with this sort of thing is that it really depends upon the sources used, but the fact that the ones I provided are either above or below the ranges in all the sources I could find, thus meaning they can't even be considered an average of the available resources, makes me wonder about the accuracy of the rest of the information that is not so easily checked (Initiative, defense, hardness, etc.)