Old Car Vs New Car Calculator for your Android phone helps you calculate the economic feasibility of cashing in and trading up. It’s unique because it factors in increases in the cost of gas over time, which can give you a better idea of how much you’ll be dishing out at the pump in the future. The app defaults to a 10 percent annual increase, or you can enter your own custom percentage.

The app makes the whole calculation process pretty easy by just firing straightforward questions at you — questions like “What is the price per gallon of fuel that you pay?” or “What’s the year, make and model of your vehicle?”

I’ve noticed that some of these questions are worded awkwardly (see above), which can make you go “huh?” the first time you read them — but, for the most part, these are not difficult questions. The best thing you can do to make the comparison calculation is to do a little research in advance. Know anything about your annual insurance premium? How many miles your car gets to the gallon? How about the MPG that car you’re looking to buy gets? Know how many miles you drive every year? Or how much you spend on maintenance? These are all things you need to know.

To determine how much you can get for your car at trade-in, the app boots you out of the app to the Kelley Blue Book website. I was a little disappointed that the app didn’t have an in-app estimate option or that it couldn’t link up with the Kelley Blue Book app I already have downloaded onto my phone. I also found it frustrating that the app completely closed up on me when I came back to fill in my estimate.