Officials of the IZOD IndyCar series have modified the Supplemental Guidelines for Engine Manufacturers for the 2012 season.

Under the amended rule 3.8, which went into effect beginning April 30, teams can only pair with one manufacturer in any single season unless approval is granted by IndyCar.

This decision was triggered by the decision of Lotus to reduce its engine supply programme from five cars to three, with Bryan Herta Autosport and Dreyer & Reinbold set to run Chevrolet or Honda engines from Indianapolis onwards. HVM and the two-car Dragon Racing team remained contracted to Lotus.

Photo: LAT for IndyCar

"The intent of the rule is to try to help build a partnership between a team and its engine manufacturer," said Trevor Knowles, IndyCar's director of engine development.

"Having a long-term commitment helps ease concerns about confidentiality of any information the manufacturer may share with a team. It also limits a manufacturer's ability to drop a team from its line-up if they are going through a bad patch. Without it, one would see a drift of all the teams with the best results to the manufacturers with the best results creating a big imbalance across the field.

"However, we have to be pragmatic and realize that there have been and will be times when a team and its manufacturer have to go their separate ways to their mutual benefit. This change allows that to happen while still maintaining control of the process."