GM has the following recommendations for 200, 500 and 1500 miles. They say that following these guidelines is recommended as parts have a break-in period and performance will be better in the long run.
For the first 200 Miles (322 km):
To break in new tires, drive at moderate speeds and avoid hard cornering for the first 200 miles (322 km).
New brake linings also need a break- in period. Avoid making hard stops during the first 200 miles (322 km). This is recommended every time brake linings are replaced.
For the first 500 Miles (800 km):
Avoid full throttle starts and abrupt stop.
Do not exceed 4000 rpm.
Avoid driving at any one constant speed, fast or slow, including the use of cruise control.
Avoid downshifting to brake or slow the vehicle when the engine speed will exceed 4000 rpm.
Do not let the engine labor. Never lug the engine. With a manual transmission, shift to the next lower gear. This rule applies at all times, not just during the break-in period.
For the first 1500 miles (2414 km):
Do not participate in track events, sport driving schools, or similar activities during the first 1500 miles (2414 km).
Check engine oil with every refueling and add if necessary. Oil and fuel consumption may be higher than normal during the first 1500 miles (2414 km).