A Mercedes belonging to Esat Digifone chairman Mr Denis O'Brien was set on fire outside his Dublin home last might.
Gardai in Donnybrook investigating the incident are said to be following a definite line of enquiry.
The car which is worth in excess of £100,000, went on fire outside his home in Wellington Road, Donnybrook, at 1.20 a.m.
Crews from Donnybrook Fire Station attended the blaze, which was reported by a member of the public.
Mr O'Brien was said to have been out of the country when the incident happened.
