Sometimes apps based on websites end up being more useful than the websites themselves, and this is certainly the case with the Auto Trader app. Like the website, you can use the app to scour the web for a car you want to buy. You can use the search option to enter your postcode and then tell it how far you're willing to travel to buy your second hand car.
After that, you can specify a make and model and then the price band of used cars that you want to view. You can also add in a whole host of other criteria such as colour, engine size and number of doors. You'll then be presented with a list of cars for sale to browse through. There's also a neat augmented reality feature where if you're out and about and see a car that you like, you can take a picture of its number plate and use it to look up prices for similar cars.
If you're on the hunt for a second hand car, the Auto Trader app should be your first port of call.