Which GPS has the best speed accuracy?

[a_ahmed]

Ive never had one and only saw one on my brother in laws car so i was wondering... Ive heard people tell me some of them are +-5kmhr off... true or not educate me.

I was wondering which GPS on the cheap has an acurate speed reading. I know my question is lame :o

[zoomswimmer]

I was actually wondering the same. I have one for my laptop, but the only time i look at the speed is when I'm on cruise control and it seem accurate.