British single-seater outfit Carlin investigated the possibility of joining the BTCC for 2018 before deciding against a move.
Trevor Carlin's team - which is backed by Grahame Chilton, the father of IndyCar driver Max and BTCC racer Tom - will compete in seven single-seater series this year.
It announced last month it would field a team in IndyCar starting this year, having run a team in the Indy Lights support category since '15.
Carlin also runs a team domestically in series including British F4, which races on the BTCC undercard.
Asked about rumours his team had considered a BTCC move, Carlin told Motorsport.com: "It's something myself and Grahame spoke about quite seriously, but as it happens the idea we had we couldn't quite pull off, so it's been shelved for a while."
Tom Chilton said a tie-up with Alfa Romeo had been attempted, but Motorsport.com understands the option of buying an existing team was also considered.
"There was a couple of talks and I did try very hard to get it to work, but sadly Alfa Romeo's budget had gone by that point," Chilton, who will race for Motorbase in the BTCC next year, told Motorsport.com.
"I was trying to actually get budget from Alfa Romeo to do a proper car and a proper team, and I tried very hard.
"For the future there's always that option - and when I say the future I'm talking about when the rules change again, we'll be thinking. It's that distance down the road again.
"But it's very much up in the air; Carlin at the moment is the busiest race team in Europe, they run more cars than anyone I think at the highest level, and are now obviously in America with IndyCar and Indy Lights.
"They're flat out everywhere, and it makes sense as well with some of the cars they run on the TOCA package - why not run a touring car team too?
"But at the moment we couldn't make it work because we couldn't get enough funding from a manufacturer."
The Alfa Romeo brand will return to the BTCC this year through HMS Racing, which will run a Giulietta in the series through a dealer team entry.
Chilton joins Motorbase BTCC squad for 2018
Newsham announces retirement from BTCC
Carlin considered BTCC move for 2018
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