NASCAR uses about 6,000 gallons (of 110-octane E15 fuel) per race week. The United States averages 386 million gallons of gasoline per day. NASCAR runs 39 races per year (including the pre-season and All-Star races), so their usage only accounts for 0.000166% of fuel consumption in the United States (or about one out of every six-hundred-thousand gallons used).
Cowboy Stadium spends about $200,000 per month on utilities. If we assume that’s mostly electricity, that’s about 25,000 MWh, or the equivalent of an 80,000 person city.
A gallon of gas contains about 35-40 kWh of energy. So Cowboy Stadium consumes 32 times as much energy as all of the cars in NASCAR.