break in?

i just got a 04 prerunner double cab with a v6 with 4 miles and it says in the manual break in for 1000 mile and not to stay at a high or low speed for long while breaking it in but i need to take a 500 mile trip to arizona(one way) and ill average about 70mph. is this a bad idea? is it really important to not stay at a speed for a long time. thanks

Here's the opinion of a guy who built winning 4-stroke racing motorcycles. Very interesting.

http://www.mototuneusa.com/break_in_secrets.htm