The City of Phoenix's Chevrolet Spark subcompact cars have reduced maintenance costs by more than 40% over the smart cars they replaced about two years ago for parking enforcement, according to the city.

The city's four Spark cars have been set up with a full lightbar pakcage, wig wag tail lights and a portable radio charging station, said Sgt. Jonathan Howard, a Phoenix Police Department spokesman.

The Spark cars have been costing 10 cents per mile for maintenance versus the cost of 17 cents per mile for the smart cars. The smart cars needed premium fuel, which isn't offered at city facilities. Also, parts and repair costs were significantly higher for the smart cars.

"Because premium fuel is not available at city facilities, the mpg for our smart cars has not been effectively available and managed," Howard said.

The city is getting about 13.66 mpg for the Spark cars. The low fuel economy is due to the excessive idle time during enforcement activities.

A 2016 Chevrolet Spark retails for $17,200, while a 2016 smart fortwo retails for $15,400.