Busch Series
The cars used today in the Busch Series are slightly different versions of their Nextel Cup counterparts, the main differences being a slightly shorter wheelbase (105" instead of 110") and a larger spoiler (57" wide x 5.75" high instead of 55" x 4.5"). In the past, Busch Series competitors could use makes of cars not used in the Cup series, as well as V-6 engines instead of Cup's V-8s, but the cars used in the series now are very similar.

On March 6, 2005, the Busch Series held its first race outside the United States, the Telcel-Motorola 200. The race was held in Mexico City, Mexico at the Autodromo Hermanos Rodriguez, a track that had previously held Formula One and Champ Car races in the past, and was won by Martin Truex Jr..

Beginning in 2007, ABC, and ESPN2 will be the exclusive carrier of all Busch Series races, currently shown on FOX, FX, TNT and NBC. Some sponsors have cricitised the new television deal, noting a maximum of four races will appear on broadcast network television, and most likely none in prime-time; in recent years, as many as nine races in the Busch Series have aired on network television, with two 2005 races ending up in prime-time television.

Busch Series cars use fuel that contains lead. NASCAR will conduct a three-race test of unleaded fuel in this series that began with the July 29, 2006 race at Gateway International Raceway. Leaded fuel will return after that while NASCAR reviews the data collected during the test.

Once the Car of Tomorrow is implemented in the Nextel Cup series, NASCAR will begin work on changing the cars run in the Busch Series. NASCAR has been approached by manufacturers about using differently shaped and named car models as the basis for the cars in the Busch Series when this change is made. NASCAR has been receptive to the idea.