"It's a great result - not just for me personally but it's obviously important to get this win with what's going on in the background with the team," he said.
"I know how much Richard (Emery, Nissan Australia CEO) and Mitchell (Wiley, sponsorship manager) from Nissan wanted this and how important this is for the next few months or whenever it happens.
"We've been working so hard.
"It's something that I promised the team. I knew we were very close to making this result and it's great that we made it all work today."
Caruso started the race from second on the grid and showed nice early pace, jumping Holden's pole sitter, Shane van Gisbergen, during an eventful opening lap.
Van Gisbergen regained the lead on lap five following a safety car, which was triggered by a stray door from Garth Tander's Holden Racing Team Commodore.
But the Kiwi copped a drive-through penalty for an early move at the restart, costing him potential victory.
He finished 16th.
Caruso's triumph brings to 10 the number of different winners from 12 races this season, and hands Whincup the championship lead.
Ford's Mark Winterbottom had held a 27-point buffer at the top of the standings but his ninth place wasn't enough to keep him at the summit.
He slips down to second overall - 18 points behind Whincup.
"It's a long way, so we don't look at the championship," six-time title winner Whincup said.
"I'd certainly rather be leading than anywhere else, so I'll take that. Let's see if the old man can do something tomorrow."