no. the car in the other lane should be a safe distance behind so that your changing lanes doesn't cut him off. if someone is changing lanes i'd much rather have him slip in behind me than speed up and cut me off. also, if everyone is going at the speed limit, then in theory you can't speed up to change lanes. i'd like to hear from a driving instructor on this. i may be totally wrong, but i'm just speaking from experience. i don't know what the book says. My driving instructors said to accelerate into the lane, and they explained it like I did. If you need to slow down to get into the other lane, do it in your own lane. It's not safe to change lanes while braking. You don't punch the gas and slam over into the lane, it's just that you push the car over there with some power so you are done with your maneuver quickly and at the proper speed when you get there. Also, the speed limit is usually academic. Traffic very rarely moves at the speed limit in every lane.