"All the midget guys like racing at Baypark. It was a nice fast race track tonight with just a few ruts in turn three. I had a good run here last year but I crashed in the feature."
Gwilliam, who was a Baypark winner last summer, was closing rapidly and set the fastest lap of the race on what turned out to be the final lap.
"It would have been nice to do the whole 30 laps," he said.
"We've had a season of ups and down but a good result here gives us some confidence for the last part of the season."
Former United States Auto Club National Midget champ Jerry Coons Jr said his engine "wasn't 100 per cent".
He had trouble with a valve cover oil leak in the heat races and eventually finished fifth in the main event.
"It's a great facility (Baypark) and they've made us feel welcome. If they had worked the track a bit more it would have been a lot better but it was greasy and there was only one line," said Coons.
The night began badly for Super Saloon racer Matt Smith (Thames) with his Corvette being returned to the pits behind a tractor after he'd clobbered the wall during warm-ups on a muddy track.
With the right front suspension repaired he qualified on the outside of the front row - alongside top qualifier Gavin Dyer - for the South Pacific Super Saloon Car Championship and then led the shortened 20-lapper (originally scheduled for 30) from start to finish.
Dyer was second and Karl Hanlon was third.
A win from the front of a 20-car grid in race one and then two third placings later in the night was the winning recipe for Rotorua-contracted Scott Fredrickson in the BoP Stock Car Championship.
Fredrickson finished three points clear of Rotorua's Damian Orr with Baypark racer Joseph Carter one point back in third place.There was a clean sweep of the podium by Baypark drivers at the New Zealand Saloon Car Grand Prix which was held at Auckland's Waikaraka Park on Saturday night.
Tauranga's Brent McClymont finally won the only major saloon title that has eluded him - he had finished runner-up on four occasions in the past six years - when he led home Tauranga's Steve Cowling and young Gisborne racer Dan Corrin in the final.