The NASCAR Xfinity Series (NXS) is the second-highest level of professional competition in NASCAR, and it is promoted as NASCAR´s “minor leage” circuit. NXS races often take place the day before a NASCAR Cup Series event.
In the past, this series has been known as the Budweiser Late Model Sportsman Series, Busch Grand National Series, Busch Series, and the NASCAR Nationwide Series, depending on the sponsorship situation. The current sponsor is the consumer cable brand Xfinity (owned by Comcast).
Until 2005, the races of this NASCAR series only took place within the United States, but this changed in March 2005 when the Telcel-Motorola 200 race was held at the Autodromo Hermanos Rodriguez racecourse in Mexico City. The first race in Canada took place at the Circuit Gilles Villeneuve in Montreal in August 2007.
Background
The Xfinity Series has its roots in the NASCAR Sportsman division, a division founded in 1950 for races on short tracks. The cars did not have to be current model cars, and quite a few modifications were allowed (but not as extensively as for the NASCAR Modified series). Eventually, the series became the Late Model Sportsman Series and began holding events at larger tracks, including the Daytona International Speedway.
The modern version of this series was formed in 1982 and named the Budweiser Late Model Sportsman Series, as it was sponsored by the Budweiser producer Anheuser-Busch.
In 2016, the series implemented the seven-race Chase system, inspired by the system used for the NASCAR Cup Series.
Race fields
Prior to 2013, there were 43 cars per race.
For 2013-2018, there upper limit was 40 cars per race.
For 2019, only 38 cars were allowed per race.
For 2020 the number was lowered to 36, but fields were also temporarily increased to 40 cars to accommodate part-time teams that were otherwise unable to qualify because the normal sessions had been cancelled due to Covid19.
Xfinity Series cars
Current specifications (2020)
| Chassis | Steel tube frame with integral safety roll cage |
| Wheelbase | 110 inches |
| Lenght | 203.75 inches |
| Width | 75 inches |
| Height | 51 inches |
| Weight | 3,200 lbs minimum without driver
3,400 lbs minimum with driver |
| Steering | Power, recirculating ball |
| Seat belt | 6-point |
| Head restraint | HANS device |
| Engine displacement | 358 cu in Pushrod V8 |
| Power output | 650-700 hp unrestricted
Approximately 450 hp restricted |
| Transmission | 4-speed manual |
| Torque | 700 N⋅m (520 ft⋅lb) |
| Fuel | 90 MON, 98 RON, 94 AKI unleaded gasoline provided by Sunoco 85% + Sunoco Green Ethanol E15 |
| Fuel capacity | 18 US gallons |
| Fuel delivery | Carburetion |
| Carburetor size | 390 ft³/min (184 L/s) 4 barrel |
| Compression ratio | 12:01:00 |
| Aspiration | Natural |
| Tires | Slick on all tracks
In case of rainy conditions, rain tires are used on road courses |
The cars used for the NXS races today differ in many ways from the ones used for Cup Series races. They do for instance have less powerful engines, their wheelbase is shorter (105 inches instead of 110 inches) and they weigh less. In 2012, the fuel delivery system for Cup Series cars was changed from carburetion to fuel injection, but NXS cars still use carburetion.