No!!! When I bought my 08 LTZ I just drove it normally, took two trips and drove 70 on the intrestate and everything inbetween, only thing I did was change the oil at 500,1500 and switched over to synthetic oil at 3,000 she runs beautifully
The manual states to vary speeds for the first 500 miles. You don't want to take a road trip, set the cruise at 65 and drive 200 miles like that. For the first 500 you want to vary your speeds (drive normally). Also they do not want you reving the engine or going full throttle for the first 500 miles either.
That is an old way of doing things and not necessary with modern cars. Most newer cars are basically broken in already. You only need to do a little bit of work. I would be mindful to not be too hard on the engine for at least 500 miles, but in trying to get the most out of my car I waited about 1500 miles. Now, I did go over quite a bit and do some passing acceleration, etc., just nothing crazy. I basically drove it like I always do & will. The one thing you might want to do is change the oil at 500, 1000, 1500, 3000 or a combination of 2 or 3 of those to get the old oil out, any metal shavings from manufacturing out, and the oil you want to run from then on out in the engine.
Just dont go nuts for 1000 miles. Change the oil maybe at 1k and then again at 3k if you want to run synthetic.
The problem isn't so much about breaking in the engine but the transmission and differential. That is why they state no forced downshifts, etc for the first 500 miles. That lets the gears wear in properly. The gears take a minimum of 250 miles to break in.