It's not the engineers that set these tolerances for oil burn, it's the warranty claims department and they set the allowable oil consumption so high so that they don't have to repair engines.

I had a new GM product that used a bit over 2 quarts between oil changes (4-5k miles) and the dealer told me that was normal and within spec (1qt per 1k miles), it didn't make me happy though and I reported my displeasure to the service manager and than the general manager they ended up replacing the engine and the new one doesn't use any oil between changes.
Moral of the story is; just because the manufacturer says it's within spec doesn't always mean that you have to settle for that.