What is the difference between Audi A5 model years?

I'm in the market for a used Audi A5 and I see a lot of different model years. Are there any major differences in features or performance that I should be aware of?

The Audi A5 was first introduced in 2007 and has undergone a few updates since then. One of the key changes was in 2012 when the engine was upgraded to a more powerful and efficient 2.0-liter turbocharged four-cylinder. This means that models from 2012 and newer will have better performance and fuel economy compared to earlier years.