<P> The era drew to a conclusion in the 1970s . 1972 brought so many rule changes, it has prompted many to consider this year as the start of the modern era of NASCAR racing . In addition, R.J. Reynolds (the tobacco conglomerate) took over as the major sponsor of NASCAR racing (changing the name to the "Winston Cup") and they made a significantly larger financial contribution than previous sponsors . Richard Petty's personal sponsorship with STP also set new, higher standards for financial rewards to driving teams . The sudden infusion of noticeably larger amounts of money changed the entire nature of the sport . </P> <P> The 1973 oil crisis meant that large displacement special edition homologation cars of all makes were suddenly sitting unsold . Through the balance of the 1970s until 1992, the factory stock sheetmetal over a racing frame meant the cars looked very much like their street version counterparts . It can be said that 1993, with the addition of ground effect wrap - around type spoilers marked the beginning non-stock sheetmetal and from that point forward, stock cars were quickly allowed to differ greatly from anything available to the public . Modern racing "stock" cars are stock in name only, using a body template that is vaguely modeled after currently available automobiles . The chassis, running gear, and other equipment have almost nothing to do with anything in ordinary automobiles . NASCAR and the auto manufacturers have become aware of this, and for 2013 each brand (Chevrolet, Dodge, Ford, and Toyota) have redesigned their racing sheetmetal to more resemble the street models of their cars . </P> <P> The most prominent championship in stock car racing is the Monster Energy NASCAR Cup Series, named after its sponsor Monster Energy . It is the most popular racing series in the United States, drawing over 6 million spectators in 1997, an average live audience of over 190,000 people for each race . </P> <P> The most famous event in the series is the Daytona 500, an annual 500 - mile (800 km) race at Daytona Beach, Florida . The series' second - biggest event is arguably The Brickyard 400, an annual 400 - mile (640 km) race held at the Indianapolis Motor Speedway, the legendary home of the Indianapolis 500, an open - wheeled race . NASCAR also operates the Xfinity Series, a stock car junior league, and the Camping World Truck Series, a junior league where pickup trucks are raced . Together the two car - based series (Monster Energy Series and Xfinity Series) drew 8 million spectators in 1997, compared to 4 million for both American open - wheel series (CART and IRL), which merged in 2008 under the IRL banner . In 2002, 17 of the 20 US top sporting events in terms of attendance were stock car races . Only football drew more television viewers that year . </P>

When did nascar stop using real car bodies