There is a limit on the amount of fuel a driver can carry. A standard NASCAR fuel cell is 22 gallons, but they can mandate a smaller cell for any race. They also set the size and length of the lines that run between the fuel cell and the engine, and also the path the lines take through the car. They do this because Richard Petty once presented a car that had the fuel lines routed through the frame rails to make the car neater...but when they checked further they found the frame of his car was full of gasoline. When they told him he couldn't do that, he presented a car for inspection the next week that used fifty feet of fire hose as a fuel line.
There is no limit as to the amount of fuel a driver can use. In IndyCar they've always had a tank of fuel sitting in the pits and when it was empty you couldn't race anymore. NASCAR doesn't think that's safe, so each track they use has a gas station in the infield where teams pick up fuel after each pit stop.
Sunoco has been the official fuel supplier for Nascar since 2004.
In fact, NASCAR is planning a move to fuel injection. This will happen in 2011 or 2012.
45 mph
Metallica did feature their song "Fuel" in NASCAR on FOX broadcasts in 2001, but bands do not actually make deals with NASCAR itself.
I don't believe that NASCAR is using ethanol. I know F1 race cars use it.
Nascar raised the age limit to 18 years old in 2002. Kyle Busch drove at 16 in the Truck Series in 2001. He didn't race again until he turned 18 in 2003.
In Nascar he holds the fuel overflow catch can.
Fuel by Metallica
The can weighs 16.4 lbs empty and about 58 pounds full. The catch can weights about 5 lbs, not for sure.
On average a NASCAR get 4-6mpg, so during a 500mile race they would consume 80-125gallons of fuel.
Indycars and F1 cars use alcohol-based fuels. NASCAR uses high-octane gasolines.
The Nascar crew member holds the catch can to retrieve the fuel that can spill from a vent on the back of the car during pit stops. Starting in 2011, Nascar has eliminated the catch can in all three series.