I'll take issue with the Vincentric link, at least with the numbers for CT (where I live).
We have a 6% sales tax, from which the fortwo is exempt because it is DOT rated to achieve 40 MPG. But we also have Personal Property Tax. It's based on a mil rate applied by your town (each is different) to a value assigned by a "blue book" the state uses. Your tax can differ markedly depending on where you live.
I don't think that they used PP tax in their calculations. We have a Mini that is 2 years old this month. It cost $18,900, and so far I've paid about $900 in yearly property tax, plus the initial 6% sales tax. So I don't see how the Toyota could be $1600 for five years unless it's just sales tax. And the Audi has an MSRP of $120,000. On top of the $7200 sales tax, my town would hit me for about $3200
the first year on property tax. It would go down a few hundred each year, but the total for 5 years would be over $12k, plus the initial sales tax. Their estimate is about $9k.
I'd take that Vincentric estimate with a grain of salt.