The police want abandoned cars to be reported
Most of the cars targeted by the arsonists had been abandoned.
Nobody was injured but Avon fire brigade warned that the arson attacks were putting people's lives at risk.
Brigade spokesperson Jeff Hutchings said: "When firefighters were dealing with these fires, resources were taken away from potentially more serious incidents."
Fatal consequences
Mr Hutchings said: "Unfortunately this was a bad weekend, although we have had other weekends like this before.
"It is a big problem and we are keen to highlight how dangerous it is.
"People's lives are being put at risk and someone could die as a result of this."
Avon Fire Brigade is working in partnership with Avon and Somerset Constabulary and local councils to raise awareness of the problem.
'Hot spots'
A scheme to tow away abandoned cars within 24 hours of being reported has already proved a success after it was piloted in two areas in south Bristol.
The government-led Arson Control Forum has now allocated £30,000 to expand the initiative to cover the whole of Bristol.
Mr Hutchings said: "With the additional funding, we will be able to hit hot spots across the area where cars are regularly dumped and set on fire.
A spokesman for Avon and Somerset Constabulary added: "We want the public to get involved and contact us to get the cars removed before they become a target for anyone who may want to destroy them."