WOW... no actually a REAL DRAG CAR would NEVER use a 30 gal tank... they would use THE MINIMUM size possible to get down the track... no you wouldn't run one in a street driven car cuz you wouldn't make it to the next gas station...
it saves weight by holding LESS LIQUID... pretty simple right?
do a search on google or summit racings list... yes they sell large size fuel cells so that you can meet safety requirements at the track in your daily driven car but NO drag car would have a 30 gal tank... that would be dumb... I know people who'd drop out there tank at the track and run their fuel cell while they were there.
here is a good faq on fuel cells...
http://www.fuelsafe.com/FAQ.htm