In GT1, the field appeared to be shrinking. Corvette Racing's commitment was certain, but Aston Martin Racing, now running Pirelli tires instead of Michelin, was only able to promise Sebring in the beginning, later stating they'd also run Houston and Mid-Ohio in preparation for Le Mans. Their involvement for the rest of the season was left as merely a rumor. ACEMCO Motorsports's future in ALMS was also uncertain, with the team scrounging for cash to be able to continue racing. Former GT1 team Carsport America finally folded following the 2005 season, with their Dodge Viper GTS-R greatly outdated. The involvement of Maserati in the series was also pulled due to the cancelling of the project by the corporate heads since it never reached its initial plans, and the continued restrictions put in place by IMSA.