Jack Cottle, of Durgates, Wadhurst, East Sussex was arrested after footage of a VW Polo being driven into a Fun Cup race on 14 June was posted on YouTube.
He admitted causing a public nuisance by driving on to a live racing circuit causing it to be stopped and putting competitors in harm's way.
Cottle is to be sentenced in November.
Judge Martin Joy told him: "Motor racing is an inherently dangerous sport and quite plainly it was a matter that put persons at risk for their lives.
"You must understand that the court will be considering a custodial sentence."
The white car, carrying two passengers in addition to Cottle, was seen in the video travelling along the Kent track at high speed as other cars passed by during the last 30 minutes of the four-hour race.
The footage has been viewed more than a million times online.
Prosecutor Keith Yardy told the court: "As a result of his actions, the race was brought to a stop. He was interviewed. He said he was dared to do it and was sorry but would do it again."
However, defence counsel Ailsa Williamson said Cottle was "an immature man" but had the support of his family who attended court with him.
She said: "He was dared by friends. This was a foolish prank that should never have gone this far and he deeply regrets his actions."
A 22-year-old man who drove his girlfriend's car on to the Brands Hatch circuit during a race could face jail.