Coronel finished fourth in the 2011 drivers’ championship with the team then fifth last year and will battle for the main driver's title in 2013.
O’Young has previously driven for SEAT and Chevrolet in the series and will look to fight for the Yokohama Trophy independents' title.
Team principal Roberto Ravaglia said: “We are very confident while looking forward to the new season. Tom is part of our family and we are pleased to welcome Darryl in the team.
"They are both experienced drivers; Tom has the potential to fight for top three in the drivers’ championship and Darryl for the Yokokama Trophy title."
Coronel believes the BMW 320 TC is an improvement on the previous cars he has raced.
“During the winter, they have tried everything to make the BMW lighter and better," he said. "We are now quite close to the minimum weight, which certainly will give us an advantage.
"We are aiming at top-three results in the races and in the championship. Of course, the opposition has been working hard, too, but I am very confident that we can be among the front-runners."
O’Young is confident about making the switch to rear-wheel drive.
“I am excited to join ROAL Motorsport," he said. "I have admired Roberto and his team for many years in the WTCC, and to have an opportunity to work with them this season is perfect.
"I have built a rear-wheel drive experience in GT racing, so I feel the BMW will suit me well. I'm looking forward to begin testing with the team, and I will work hard to deliver the best results.
"This will be my fourth WTCC season and by now I have the experience to fight for the Yokohama Trophy title.”
The team will test at Vallelunga, Italy on February 21 and 22.