You should only edit the DRIVERS2.TXT file, not DRIVERS.TXT. Names of the chassis and engines can be changed using the CHASS and ENGIN lines (and you can add additional chassis and engines, despite the warning in the DRIVERS.TXT file indicating that it's not possible). The various DINFO (driver info) lines contain the driver's car number; the driver's chassis' index from the CHASS list (0 = Lola T9200, etc.); the driver's engine's index from the ENGIN list (0 = Cosworth XB, etc.); the driver's tires' index from the TIRES list (0 = Goodyear, 1 = Firestone); four pairs of numbers from 1 to 999 representing the driver's power, traction, drag, and aggression ranges (the higher the number, the "more" the attribute; the closer a pair of numbers, the more consistent the driver); and self-explanatory driver information, using "_" for blank spaces.

The power, traction, drag, and aggression settings do not seem to affect the player's car at all. Note also that DRIVERS2.TXT values can be easily changed with Dane Johnson's Windows-based CRHQ utility.