They torched a Ford Fiesta in Samuel Road, Norfolk Park at 1.50am today and a Volkswagen Golf in Billingley Lane, Middlecliffe, Barnsley, at 1.10am.
Last night, a Vauxhall Astra was set on fire in Limb Lane, Dore, Sheffield and on Sunday a car was set alight in Vicar Lane, Woodhouse and a Ford Fiesta was torched in Park Road, Barnsley.
Firefighters dealt with a Volkswagen Golf fired in Colley Road, Shiregreen, Sheffield, on Saturday night and a Toyota set alight in Coronation Road, Stainforth, Doncaster, earlier in the day.
Investigations are also underway into a number of other recent arson attacks including a wheelie bin set alight in Victoria Road, Edlington, Doncaster; a tree set on fire in New Street, Dinnington, Rotherham; a hedge fired in Green Lane, Instoneville, Doncaster and garden waste set alight in Albert Road, Heeley, Sheffield.
A fire was started in an industrial skip in Oaks Lane, Kendray, Barnsley and piles of rubbish were set alight in a derelict building in Kelham Island, Sheffield; in Hopewell Street, Stairfoot, Barnsley; in an empty garage in Halliwell Crescent, Parson Cross, Sheffield and in a derelict building in Shiregreen Lane, Shiregreen, Sheffield.
Grassland was also set alight in Pearson Crescent, Wombwell, Barnsley.
Anyone with information call South Yorkshire Police on 101.