Southern 100 organisers say they saw a 50 per cent jump in the number of visitors coming to the festival last year.
A survey carried out by the Department for Enterprise says 4,770 saw the Billown racing last July - spending an average of £434 on their trip.
It means the festival's estimated to have brought just over £1.5 million into the Island's economy last year.
In its report, the department says 79 per cent of visitors came from England, with 19 per cent from the rest of the British Isles and just two per cent from further afield.
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