V.W.
My son is 14. If he is generally and has BEEN generally respectful of you the majority of his life, try not to sweat it too much. His hormones are raging, he is trying to distance himself from his "mommy" and grow up, and well, he's a teenager, pretty much sums it up.
If he has always had disrespect issues, then that is another matter. But if this is him flaking out on you in just the recent history, try not to over think it.
My husband took my son for his first driving lesson today (without telling me first) in MY car. He just turned 14. I have a 6 speed manual transmission.
There are a LOT of changes that are coming over your son. Try to relax and let a little bit go...