It absolutely does work, running it in 7 track cars ('00 328Ci, '06 M3 ZCP, '90 M3, '06 Z4M Coupe, '94 MR2 Turbo, '99 M3 S50B32 Euro, '05 S2K; oh, and a 2006 Miata w an LS7 swap), and during sustained high speed driving @ track, coolant tempo decreased anywhere from 8 to 21 degrees Fahrenheit.
This is with anywhere from pure water to 35/65 coolant to water.
For a street car, it can give you a few precious extra seconds to pull over and turn off a car should it begin to overheat.