at 2900 monthly income, you have 428 in monthly expenses, bringing your discretionary down to 2472. are you planning on keeping your chevy or trading it in?

If you're keeping it, you'll have to pay for insurance on both cars. There's usually a discount with car insurance companies when you have multiple cars, but it will still eat at your finances. If you're trading it in, or even doing a pick and pull thing, you'll be able to put that as a part of a down-payment on your Mazda, which will your reduce monthly minimum.

Mazdas are really fuel efficient cars, so I think you picked a good make and model especially since you have a bit of a commute. I'm not so sure about the year. You could shop around for a 2014 give or take and go for a less expensive car.

Is there a reason you and your mom aren't on the same phone plan? There's usually a family discount for adding another line to an existing account.

If you really really want a newer model, I think you need to save quite a bit to bring your monthly down to a manageable level. If you saved 10k, you'd have a 15k loan, at 5.4%. If it's a 60 month term, you're looking at 285.83 monthly.