Does the 2012 VW GTI have a timing belt or chain?

The 2012 Volkswagen GTI uses a timing chain rather than a timing belt. Because it uses a timing chain, it usually doesn't need to be replaced unlike the belt. The only reason why it would ever need to be replaced is because of total failure but that doesn't happen too often. The reason why belts need to be replaced and chains don't is because that the belt is on the outside of the engine and is exposed and the chain is in the engine and not as exposed and gets help with lubrication from engine oil. If You don't regularly do oil changes then the chain can end up failing and will probably need to be replaced. You can inspect the timing chain by looking at the tension of it and inspecting the sprockets.