The phrase "gentleman drivers" refers to individuals who participate in motorsport as drivers but are not professional or paid. They are typically rich or wealthy individuals who pursue racing as a hobby or passion. Full definition
«These are gentleman drivers who know what their capacities are, and they don't over drive their capacities,» he said. (weathertechraceway.com)
[4] It is a designation to recognize gentlemen drivers that compete in the GT class. (en.m.wikipedia.org)
The interior is stripped out, and receives a full bolt - in rollcage treatment to keep things safe when gentlemen drivers with more money than skill inevitably stuffed their new toy into the wall. (automobilemag.com)