Have you heard this phrase before?- The cheapest car is the car you already own.
If you are going to live on one income, you need to be satisfied with the car you have. You need to be okay with seeing friends from college and still be driving the car you had in college! Let go of that pride! It's okay- you own both of your cars and have no car payment and that is cool.
We bought Casey's car 11 years ago- it was used. My van, we did purchase new, and we have one payment left on that (probably not a choice we'd make again). When it comes time to replace Casey's car, we will pay cash for it. When we make that final van payment next month, we will save up that money that would go to the payment until we have enough cash to buy a car for Casey when his finally conks out.
Living on one income requires sacrifice. It is okay! God honors these sacrifices. Driving a new car means nothing when you have to miss your child's school play because you have to work. Keep your goal in mind and the pain of sacrifice becomes so worth it!