Well title. My list is only contained with Protagonists who works the best as Drivers in my opinion. You can named other protagonists who aren't in the list/pool as well. Here's my list:
1. Franklin Clinton: A pure Getaway Driver. He's able to survive from military onslaught with a Dime. Not to mention, The Army had a few Rhinos as well.
2. Carl Johnson: He beat Claude and Cesar who are Street Racers. He's basically a Franklin prototype in the term of Driving.
3. Claude: He got the job done when Joey Leone hired as a Getaway Driver. He's a street racer after all.
4. Huang Lee: He's able to compete with the best Street Racers in the city and smashed their cars with ease.
5. Mike (GTA Advance): He participated in Liberty City Street Races. Make him one of the best Drivers in the series.
HM: Johnny Klebitz (would love to put him in the list if he likes to drive cars as well), Toni Cipriani (has a few cool moments with cars), and Luis Lopez (pretty much the best driver out of IV trio although he's more of a Pilot).