Pat, some of the racing orgs are using mechanical means/temp strips to check mandated fuel temp range but most of the small circuits simply require that all the fuel used in the event come from the same source. Usually an 'in house' fuel depot or some other subsidised source. Fuel checks, post event, are normal even in SCCA these days.
"Cool Cans" and other "'60's" innovations worked for drag racing but are of no use in other, longer race events. Once the fuel warms up, things lean out. Not usually a big deal as the CC's were not all that efficient in the first place. Jag and other street cars have used the onboard AC's to cool the fuel at the fuel rail. I assume this practice may still exist but to what purpose?
Massa10---The use of chilled fuel was to improve speed and et performance in drag racing and later to get a more dense fuel into fuel cells/tanks in racecars that have fuel quantity limitations, eg. NASCAR, Indy, CART etc. Dense=more, more=fewer pit stops, fewer pit stops---Well, you get the idea.
Rod