Some of the vehicles were painted black, while others bore a strange black and white paint scheme designed to make contour lines difficult to discern. But it wasn't the color of the cars that drew the most attention during a tire test of 2013 models held at Martinsville Speedway – it was the weight.

Four Sprint Cup teams descended on the Virginia short track Tuesday for the opening session of a two-day Goodyear test designed to shake down 2013 cars and give the tire supplier information on which to base their compounds for next season. Key in that effort is the removal of 100 pounds of weight from the next-generation vehicles, including 60 from a right side that in the current models is infamous for stressing tires on that part of the car.

Although the impact of that weight removal isn't felt as much on a short track, the hope is it pays greater dividends on a high-speed track like Michigan, where a resurfacing led to blistering that prompted Goodyear to make a tire change on the night before the race in June. Less weight on the right side may also allow teams to employ softer tires, which drivers hope will translate into better racing.

"Taking the weight out is going to be easier on the tires," Martin Truex Jr. said. "It's going to allow them to soften the tires up, get some more tire wear without having tire problems. It's going to take heat out of the right-side tires. It's going to do a lot. These cars are big and heavy ... and we've seen how much more difficult it's been for Goodyear to build a tire for when you go to a fast track like Michigan and places like that. The technology they have today at Goodyear to build tires is so far superior to what they had five or six years ago with the old car, yet we see more tire problems today, and that's just because of the weight. The high center or gravity puts so much stress on the right-side tires and not enough on the left, so I think it's going to help."

Carl Edwards agreed. "We have heavy race cars that make a ton of downforce -- almost a literal ton of downforce -- and a relatively small tire, so Goodyear is put in a very small box where the tires have to make grip," he said. "But they can't make so much grip and make so much heat that they come apart like they were at Michigan, so something has to give. You either have to make the tires wider and have a bigger contact patch, or the cars have to be lighter, or they have to have less downforce. I think NASCAR recognizes this."

Teams started Tuesday's opening day of testing with cars at the standard weight of 3,450 pounds, and went with the 2013 weight and distribution in the afternoon. Ultimately, Truex said, weight will come out of lighter parts like the hood, roof and rear decklid, areas that will be specific to each manufacturer. With the cars still evolving toward next year's Daytona 500, teams removed it Tuesday however they could.

The effect? "We went a little quicker," Jimmie Johnson said. "Some small handling characteristics, but nothing out of the ordinary. I think as the new car develops, there are a lot of areas where the weight will come out naturally. ... I think as the body gets developed, a lot of overall weight will come out of areas that are high. That will be helpful. We just literally took it out of the left rails. So from a weight front and rear percentage, maybe not ideal for the situation and what we'll have in the future, but took the 100 pounds out and went like two-tenths faster, which is what we kind of thought it was going to do. Nothing out of the ordinary."

And not a surprise on a relatively low-speed track like Martinsville. The benefit on larger layouts, though, will be evident. "We're all real confident that we don't need to develop it. We just know it's going to be better," Johnson said.

The 2013 cars were tested for the first time last November at Homestead-Miami Speedway, but this week's session at Martinsville is the first since NASCAR gave manufacturers the green light to begin building parts for next season. Chevrolet, Ford, and Toyota were each represented. More tests are planned for larger tracks in the fall as NASCAR zeros in on specific parts like the rear spoiler and front splitter, whose sizes for next season have not yet been determined.

"That's still in development," said Brett Bodine, NASCAR's director of competition for research and development. "We hope to have that narrowed in by the time we do next tire test at Texas in October. We feel pretty confident we'll be making some adjustments, but what those adjustments are right now, we're not decided on."

The weight reduction, though, appears a given. "It's just the right thing to do," said Bodine, who added that lighter cars will have additional advantages such as reducing stress on brakes and lessening the impact of an accident. The greatest benefit, though, may be visible on the race track.

"The thing I like most about getting weight out of the car and aero off the car is, we can come with softer tires and have more falloff," Johnson said, "and I think more falloff will put on better racing."