This is very frustrating to me also. I now own a X940BT. I previously owned am older model AVIC F900BT that I let go when I sold my truck. That model not only displayed the speed limit on the streets and highways but also your present speed in this format. 60/65 I sure wish Pioneer would do this for all their units. I really miss this. The interstate signage displayed was much better.
I also have to say the older model had much better maps. The zoom features were much better, the streets didn't disappear when zooming out etc. The software in general seemed to be much more stable and user friendly.
Hopefully the AVIC team reads these posts!