In a gimmick move intended to add excitement to the show, NASCAR will use heat races for the first time in the Xfinity Series on Saturday at Bristol Motor Speedway.

The heat races will set the field for the main event, and by trying it in the second-tier series, NASCAR doesn't have as much to lose. The heat races have been extremely popular for the Truck Series, which uses them to set the field at the Eldora Speedway dirt track. But this will be the first time NASCAR tries it with a stock car in a national series.

It will likely lead to varying strategies. Some drivers won't risk wrecking their cars on the day of the race, and others could sandbag in the heats to hide how good they are for the main event.

"It's going to be different — a lot of people are going to be racing, a lot of people are going to be just being smart to be safe for the main race," said points leader Daniel Suarez. "I'm going to go out and race."

Here's the wrinkle that NASCAR has forced teams to handle: If they wreck or blow an engine and aren't ready for the start of the main race, the team doesn't get to race.

The heat races Saturday will be the first of four Xfinity events that will use the format. All four races, at Bristol, Richmond, Dover and Indianapolis, are part of the Dash-4-Cash promotion. The format:

— Drivers will use single-car qualifying to set the heats. Odd-numbered qualifiers will run in the first heat; even-numbered qualifiers will race in the second heat.

— The heats at Bristol are 50 laps each and will set the field for the main event.

— The Xfinity Series race will go off after the heats and be 200 laps.

The race is important for Xfinity Series regulars because the highest-finishing non-Cup driver will earn a cash prize at the end of each Dash-4-Cash event. If the same driver earns two of the top finishes, the driver automatically earns a berth in the series' Chase playoff, which debuts this season.

Drivers will be banking on those finishes to secure their shot at the championship because Cup drivers have dominated the series so far this season. Sprint Cup drivers have won all six of the races this year, and four of those victories have gone to Kyle Busch.

Busch is looking forward to trying the heat races at Bristol.

"I think it will be fun for the fans, like an All-Star race, broken up into segments, with the ability to make improvements to the car in between," Busch said. "We'll have to see what that looks like and hopefully it will go in our favor."

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INDYCAR-DOMED SKIDS: IndyCar will use domed skids — curved pieces that are affixed to the bottom of the cars — for the Indianapolis 500 in an effort to prevent cars from flying into the air after spins.

Four cars went airborne in the lead-up to last year's race, and Chevrolet and Honda both agreed that the domed skids could return to the current cars. The pieces have been used on previous generations of Indy cars.

Drivers who tested at California and Indianapolis Motor Speedway used the domed skids, and the Honda camp complained the pieces made their cars too unstable while driving.

The domed skids are also scheduled to be used this year at Texas Motor Speedway and Pocono Raceway, but their return next month at Indy will likely be controversial if the Honda camp believes it puts them at a disadvantage.

To make room for the skids, the car must be raised, and that will create a reduction in downforce. Drivers want as much downforce as possible, so they'll have to raise the wings of the cars. That maneuver will add drag and disrupt the air behind each car, which is what made the Honda drivers argue the cars were too unstable in the dirty air.

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NHRA-PRITCHETT: Both Dave Connolly and Leah Pritchett were left scrambling for new Top Fuel dragster seats after Bob Vandergriff announced his sudden retirement this week from NHRA.

Pritchett won this year at Phoenix for Bob Vandergriff Racing. The team owner said he'd been considering retirement since he stopped driving after the 2014 season. He said the death of friend and team supporter Josh Comstock of C&J Energy Services caused Vandergriff to reflect on "my priorities in life.

"I've missed a lot of things in my children's lives over the years and the desire to spend more time at home with my family has weighed on me greatly the last few years," he said. Vandergriff has four children.

Connolly is seventh in the NHRA standings and Pritchett is 10th.

"It is beyond unfortunate, surprising, and a tip of a seahorse to say the least with the retirement news of Bob Vandergriff, and ultimately the doors officially closing of BVR," Pritchett wrote on her Facebook page. "I have beyond huge gratitude to Bob for believing in me, on and off the track."

Vandergriff won three national events in 17 final rounds over 16 seasons of driving in the Top Fuel category. His best points finish was fifth in 2007.