Regional development agency Advantage West Midlands provided the £1.2m grant from its allocation under the European Regional Development Fund Cluster Action Plan.
Advantage West Midlands chief executive John Edwards said: "The motor show brings in more than £30m to the economy and provides about 20,000 jobs. However, most of the visitors are here only for the day and we want to encourage more overnight stays, which will bring in extra revenue for local businesses."
Advantage West Midlands estimates that an extra 150,000 visitors could generate custom for about 2,700 local businesses valued at about £4.86m.
The fund has been mainly spent on a series of 30-second TV commercials featuring motoring personality Jeremy Clarkson. SMMT hopes the campaign, due to broadcast later this month, will help to attract more than 600,000 visitors to the show, which takes place from 27 May-6 June.
New features at this year's show include a four-by-four off-road driving course on 72 acres of woodland next to the NEC, a driving school for youngsters and stunt shows in a 4,000-seat arena.
SMMT president Tod Evans said: "The new formula brings the Sunday Times-sponsored event up-to-date and should see an increase in visitor numbers."