Who's going to pay for you to train? Who's going to be responsible for getting you there? If you're relying on mommy -- maybe it's time to get a job, and line up your own resources. Otherwise, she ends up with the deciding vote.
You might also investigate public transit options, as well as seeing if there's someone close by that you can carpool with.
Let me also take your points:
Each way. That's 50 minutes. Probably more like an hour, and I don't know what traffic is like in your area at the hours in question.
-having to sit outside for a hour (bring a book XD)
You're awfully casual with 2 hours of your mother's time, even if it's only twice a week. Maybe she's got some other obligations for that time... like cooking your dinner? (Maybe you could help with that sometimes, too?)
Her money, her gas -- guess who determines if it's a waste.
-something I really really want to get in to
-i want to do this and get better and compete later on
OK. Kind of self serving, and it begs the question of how many other things you've "really wanted to get into" that you mom's footed the bill for. And how long they lasted.
If it's something you "really want to get into" -- work to pay for it and find a way to provide your own transportation. After all, who's going to pay your entry fees and drive you to the competitions?
If you can't guess -- you're coming across in this post as being kind of immature. You really want to do this? Show your mom that you're serious by finding solutions to her complaints, not simply whining.