DAYTONA BEACH, Fla. -- Thirty-one cars, including 16 in the Sprint Cup Series, failed inspection before Thursday's practices at Daytona International Speedway.

NASCAR confiscated the teams' roof flaps, which are designed to keep cars on the ground during spins and wrecks at high speeds, for further inspection. Penalties could be possible.

The cars involved included all three Joe Gibbs Racing entries (Kyle Busch, Denny Hamlin and Matt Kenseth), all three Roush Fenway Racing entries (Greg Biffle, Carl Edwards and Ricky Stenhouse Jr.), all three Michael Waltrip Racing entries (Clint Bowyer, Martin Truex Jr. and Michael Waltrip) and both Roger Penske Racing entries (Joey Logano and defending series champion Brad Keselowski). Cars driven by Jamie McMurray, Trevor Bayne, Casey Mears, Marcos Ambrose and Aric Almirola also failed inspection.

The roof-flap spacers had been illegally machined down to reduce weight.

NASCAR inspectors made those Cup teams install new, unaltered roof flaps before drivers were allowed on the track for the first of two practices.

Inspectors then went to the Nationwide garage and found similar issues on 15 cars.

"When you find something in one garage, you communicate to the other garage," NASCAR spokesman Kerry Tharp said. "We looked into it and this is what we found."

Nationwide drivers facing possible penalties include Bayne, Brian Vickers, Reed Sorenson and Travis Pastrana.