about the track and car setup before the main race. In the aforementioned 2008 meetings between NASCAR and Detroit automakers, the automakers also called for the Xfinity Series to become strictly a developmental series, with Cup drivers prohibited from running in the junior series. The request was rejected at that time. However, in late 2010, media reports began to indicate that NASCAR may institute a slightly modified version of this rule for 2011, with Cup drivers allowed to run in Xfinity races but not to compete for the series championship. In January 2011, NASCAR.com confirmed this, adding that drivers will now be allowed to compete for the championship in only one national series in a given season, a change that also affects the Truck Series. In October 2016, NASCAR announced new participation guidelines for its three national series, limiting the number of Xfinity Series and Truck Series races that full-time drivers in its premier series will be allowed to compete in, starting in 2017. Environmental effects Fuel consumption According to NASCAR, about 6,000 U.S. gallons (~23,000 litres) of fuel are consumed during a typical Cup Series weekend. For the 2006 season, which included 36 points races, the total for the season would have been 216,000 U.S. gallons (818,000 000 litres). One environmental critic recently estimated NASCAR's total fuel consumption across all series at 2 million U.S. gallons (7,570 000 litres) of gas for one season. At race speeds, Cup Series cars get 2 to 5 miles per gallon. Consumption under caution can be estimated at 14-18 mpg, based on comparable engines generally available to the public. The rate of fuel consumption tends to be the same regardless of the actual speeds of the cars, as teams change gear ratios for each race to ensure that the engine always operates in its optimum power band; however, the fuel mileage will vary for each race, depending on the maximum speeds attained. The fuel consumption criticism dates to 1974 and the energy crisis; NASCAR responded by showing data that racing was far less consumptive of fuel than regular air travel and other non-motorsport sources of consumption. Emissions and pollution The consumption figures above provide no insight on environmental impact in terms of emissions. NASCAR vehicles are generally unregulated by the United States Environmental Protection Agency, and in particular, they have no mufflers, catalytic converters or other emissions control devices. However, some local short