WalletHub just did an article where they broke down cities and area spending on vehicles The Treasure Valley towns/cities were all ranked.

They were able to gather this data by taking the median auto-loan balance of more than 2,500 U.S. cities and compared them.

Caldwell ranked 88th, Nampa at 82, Meridian 59, Boise 42 and Eagle at 33. Which is getting pretty close to being one of the top in the nation for overspending on vehicles. They also had a display for cities with the most auto loan debt/ For example Boise has A median auto loan debt of $13,926 with an average income of $44,456.

Source: Wallethub