There are A LOT of wealthy people and it doesn't take many to make it look like everyone is wealthy. According to latest American Community Survey, there are 74,000 households in Iowa making over $200,000/year. Assuming over half live in the metro area, that's a lot of households.
And then add in all the farmers and contractors who can expense leases (better tax treatment than to buy a car), you get the massive amount of expensive vehicles.
FTR we have 3 cars: bought two with cash (hooray CF!) $24,000 and $31,000 (insurance settlement helped) and the third one has a 60 month loan at $320/month with a $10k remaining balance.