Yeah, they look like their Winston Cup cousins and now they are closer than ever, but they ARE different. NASCAR Busch Series cars are their own breed of cat and, even with only a few differences, they are a distinctive car found nowhere else in NASCAR.

Follow along as we point out some of the key differences.

Wheelbase

Depending on whom you talk to, the biggest difference is the wheelbase. Busch cars are 5-inches shorter in wheelbase than Winston Cup cars. Spec wise, that means Busch Series cars are 105 inches and Winston Cup cars are 110. Just for reference, NASCAR Craftsman Trucks measure in at 112 inches. That slight change affects the bodywork, aerodynamics, downforce, handling, gearing and even the driving style of these cars.

How builders make up that 5-inch difference varies and is either split between the front and rear or taken solely out of the back of the car. If it’s split, usually it’s 2 inches in the front and three in the rear.

The difference in that split is very slight, says Dan Rang, shop supervisor of Herzog Motorsports, which builds the No. 92 Excedrin Busch Series car driven by Jimmie Johnson.

“You could put two cars side-by-side and your average eye wouldn’t be able to see a difference,” says Rang.

Since these cars are closer together than ever, how can one tell them apart? One good indicator is the car’s battery box. They are always located on the framerail behind the driver’s seat. Winston Cup cars have their battery box mounted lengthwise, while Busch Series cars mount theirs across the frame.

Carbs are prime horsepower areas. Less cfms means a smaller amount of fuel and results in less power created. While engine builders always keep mum about numbers, Busch Series cars generally have 14 percent, or roughly 100 hp, less than Winston Cup cars.

More Details

A few more subtle differences on Busch Series cars include sitting one ½-inch lower in overall height, a wider but shorter rear spoiler and a front valance that extends down an additional half inch for a total of 4 inches. The slightest change in any of those areas can affect the car’s handling, so the driver has to adjust.

The rear-end housing may be different, too, on a Busch Series car.

“They (Winston Cup) are allowed to run what they call an offset rear end. We are not,” Rang says. “That means one end of the axle tube is actually longer than the other. It’s the actual housing and where they could put the gear in is not in the center of the rear end.”

That means axles are different lengths and fit in only one side of the car.

Evolution

Twenty years ago, Busch Series cars started out being totally different than Winston Cup cars. In the early years of the series, they used totally different bodies on the cars. While the Winston Cup cars were using full-size bodies such as Buick Regals, Monte Carlos and Thunderbirds, the Busch Series cars were using smaller, Chevy Nova and clone Pontiac Ventura bodies. The Busch Series cars were not as refined because the bulk of the schedule was on short tracks. Most of the teams were working racers with day jobs in the early years.

Engines were different, too. At one time, Buick and Ford V6 engines were the norm. Later, when the series returned to V8 motors, they were running at reduced 9:5 compression. These days, the bodies reflect Winston Cup cars with the same brands in both.

So over the years, the two classes have slowly gotten closer on equipment. Now, with most of the car’s components aligning up virtually identical, production costs have dropped along with retail prices. The similarity has an added benefit because drivers have a little less to “unlearn” when they move from the Busch Series to Winston Cup.

This similarity also invites Winston Cup teams to run limited Busch Series schedules for in-house research and development, and upcoming driver and crewmember training programs.