In the early hours of this morning, Sheffield firefighters dealt with a car torched on Atlantic Walk, Lowedges and a BMW set alight on Stradbroke Drive, Richmond.
A car was also set on fire on Howard Street, Dinnington, Rotherham.
Last night, a Kia Shuma was torched in Prince's Crescent, Edlington, Doncaster.
In the early hours of Sunday, Barnsley firefighters dealt with a Rover set alight on Osmond Drive, Worsbrough, and a Ford Focus set alight on Yews Lane, Kendray.
A Rover was torched on Badger Close, Woodhouse, Sheffield, on Friday night.
Anyone with information should call South Yorkshire Police on 101.