"This is a special opportunity for our Daytona Prototype programme," said Chip Ganassi Racing team's president Steve Lauletta.
"Any time you can pair two of the best IndyCar drivers out there in the same car makes for an immediate contender."
Laguna Seca will be Franchitti and Dixon's second Grand-Am appearance of the season, following their participation in the Daytona 24 Hours event earlier in the year.
Hartley, who sits seventh in the championship, won his breakthrough race in the series at Road America in August. He said he's happy to have another Kiwi to race against.
"I'm actually really looking forward to the race with Scott and Dario," said Hartley. "I've caught up with him [Dixon] a few times this year at an IndyCar race, and it'll be really cool to race with him.
"The racing is good and it's hard and it'll be fun. It's not often you get to race against fellow Kiwis - not even in Europe. Everyone's normally in a different series," he said.
Hartley's been pretty busy lately including getting some seat time doing tyre testing in the Murphy Prototypes car, in which he races the European Le Mans Series, in preparation for Budapest in a few weeks' time.
His Grand-Am Starworks Motorsports car has been quick all season and Hartley has had five top 10 finishes so far this year and been on the podium twice.
Despite the decision to change engine manufacturers during the series - now running a BMW power plant - the team have been in contention every time they've rolled out of the truck.
"Everything's looking good and Laguna Seca is a real driver's track.
"It looks a very quick track and some really technical corners and probably has one of the most famous corners in the US if not the world. It's completely blind and drops down and it'll be great to actually experience it in real life," said Hartley.
The young New Zealander is of course referring to the often-quoted infamous Cork Screw corner, which at times has sorted the men from the boys.
It is one of the most iconic corners in the world with a unique left right combination with a massive drop-off between the two main elements.
"The car should work really well around Laguna Seca so we're pretty confident. The BMW is a good engine and is a bit lighter than the Ford, which is always beneficial as you can get the centre of gravity a bit lower."
The Kiwi has always had an ability to get his head around a new track quickly and post fast lap times early on in the practice sessions.
It's the challenge of getting to grips with new layouts and corner combinations, which in the past has brought the best out of Hartley and this weekend should be no different.
"I'm getting better at learning circuits quicker the more I race. The knowledge bank you build up in your mind over the years makes it easier to recognise a corner on a new track that you've come across before from another track.
"You sort of piece it all together, but I've never come across anything like the Cork Screw. There's nothing like that anywhere in the world. Having said that, I genuinely love learning a new circuit and the challenge it brings," said Hartley.
