A reward of £2,000 is being offered for information leading to the arrest of arsonists terrorising Littlehampton.
Sussex Police are offering the cash following the latest incident at the weekend when a Transit van was deliberately set alight in Armada Way.
Eighteen cars were wrecked or severely damaged on November 30.
Fire crews from Bognor, Worthing, East Preston, Arundel and Littlehampton tackle the blazes which caused thousands of pounds' damage.
Police suspect the fires are linked.
PC Keith Fifield said: "We are issuing a reward for information to put a stop to this. Each fire could have been potentially life-threatening.
"We want anyone with information, whether it is suspicious activity in their area, descriptions of people or anything they believe will help us to track these offenders, to contact us."
Littlehampton police can be reached by calling 0845 6070999.
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