Only two teams – Patrick Racing and Porsche North America  – used March chassis in the 1990 PPG CART World Series. Prior to 1990 Morales Motorsports closed down and Patrick Racing took over the Alfa Romeo project with Guerrero driving the No. 20 Miller Genuine Draft March 90CA-Alfa Romeo Indy V8. Guerrero managed to qualify for the Indianapolis 500, starting 28th and finishing 23rd due to suspension damage. The team then switched to using a Lola T90/00 starting at the Marlboro 500 at Michigan International Speedway. In the race Guerrero finished in 5th place. At the end of the season Guerrero finished 16th overall with 24 points.

SeasonSeriesEvent
1990PPG Indy Car World SeriesIndianapolis 500
Driver No.Entrant
Roberto Guerrero20Patrick Racing
ChassisEngineCar Name
March 90CAAlfa RomeoMiller Genuine Draft
Scale ManufacturerCollection
1:43Onyx
Cat. No.QualityRarity
065