Online directions - time discrepancies

[4luv2cdisney]

Estimated trip times I'm getting (same routes and start / stop points) not adjusted for current traffic:

Google: 17h 29m
Mapquest: 19h 17m
Yahoo: 18h 20m

What?!?!

 

[lost*in*cyberspace]

They obviously use different formulas for calculating time. None are, or could possibly be absolutely accurate, so I don't see how the differences are an issue.

You can always do the math yourself.