Opinions vary in the NASCAR Nextel Cup garage about what today's Auto Club 500 at California Speedway will be like. New rules create many questions for drivers and crew chiefs heading into the season's second race. "No one really has a clue about the race," says Ryan Newman, who starts ninth.

They don't because NASCAR debuts several rules this weekend. Series officials cut the rear spoiler an inch to 4.5 inches. That reduces a car's downforce by about 10 percent, meaning it doesn't stick to the track as well. Some crew chiefs say the change is minimal because they regained most of the lost downforce. Some drivers say the loss will greatly affect the cars, especially in traffic.

Teams also have a new tire. Goodyear altered its tire compound for many tracks to adjust for the lack of downforce. Drivers say that the tires wear faster, meaning the car doesn't handle as well when the tires run more laps.

There's also a gear-ratio rule that limits the RPMs for teams and a new weekend schedule where teams practiced Friday and only qualified Saturday. NASCAR impounded the cars after qualifying, preventing teams from making more than the basic changes to the car before today's race. The new rules are meant to help teams cut costs. What they do is give competitors headaches.

"There are so many unknowns right now, it's hard to find out which is more important," defending series champ Kurt Busch says.

Most teams emphasized race setups in Friday's practice. A few drivers didn't fare as well in qualifying. Daytona 500 winner Jeff Gordon starts 28th, Busch is 20th and Dale Earnhardt Jr. starts 40th. Kyle Busch starts from the pole with Hendrick Motorsports teammate Brian Vickers second.

It's the race that concerns many, though. While the field is expected to spread out, as it often does at this 2-mile track, drivers are edgy about what their cars do when they're close to each other.

Dale Jarrett ran close to Ken Schrader and Earnhardt at different times during Friday's practice and says even running with another car affects handling.

"My car got looser even behind a car," Jarrett said, referring to how the car's back end slides out. "I also saw when I was behind not only Schrader, but I was behind Junior a coupe of times, that I could really make the car in front of me really loose. I think it's going to be an interesting scenario as to what's going to happen."

Jarrett says that once he got within a car length of a competitor, the aerodynamics affected both vehicles.

Earnhardt finished no better than 19th in either Cup race at this track last year. After a week off, the series heads to Las Vegas. Earnhardt placed 35th last year. So, the next two races could determine if the crew swap at Dale Earnhardt Inc. helped.

Several drivers admit that this race will serve as a better indicator of the Cup season than the Daytona 500, since that race is an oddity due to the use of restrictor plates.

"Let's not let a Daytona 500 victory fool us," Gordon said hours after his Daytona 500 win. "This guarantees nothing as far as the championship is concerned. We're going to find out a lot more what we're really made of [at] ... California."

Today, teams will start getting answers to all their questions.GRAPHIC:Impounding proceduresWhat teams can and can't do to

their cars before today's race.TEAMS MAY:

Plug in oil heater; open hood; prime oil system; back car out of garage to start; turn master switch on; open oil cooler bypass valve; start engine; close hood; set tire pressure; torque wheels; install radio and water bottle; remove or repair tape on car front.

TEAMS MAY NOT:

Enter the garage without a NASCAR official present; jack up any part of the car; add water or pressurize the cooling system; climb inside the car; adjust wedge bolts, shocks or sway bars; add fuel, oil or brake fluid; remove air box; adjust fenders, spoiler or any body components.