I think you are thinking of the Mazda LMP2 car running in the American LeMans series. Prepared and raced by B-K Motorsports, it's a Lola B07/46 Chassis and Mazda 4-banger (turboed) motor.
http://www.b-kmotorsports.com/
- Adam
Edit: Oops, missed the "Rotary" motor part.