Least expensive cars to drive

Our Volvo is really comfortable but I have come to realise why it is a "luxury" car - it guzzles fuel. Now I find myself driving the old Ford Escort most of the time as it is more economical.

Anyway, just came across this article about the "Least Expensive Cars To Drive" on the Forbes site.
The Jeep Patriot

On the list are two Toyota cars, the Prius and the Yaris. However they have included two cars that I am wouldn't put under the "economical" category, namely the Cadillac DTS and the Jeep Patriot. However according to the article, the latter has a "has a long-term cost of ownership similar to that of the Toyota Prius."