For a veteran driver, even mountain roads are an easy ride.
Tips
history
From Han Yu (Tang) 《送石处士序》: 若驷马驾轻车就熟路,而王良、造父为之先后也 — like a light carriage on a familiar road, with the great charioteers Wang Liang and Zaofu leading and following.
usage
Emphasizes ease from experience, not just speed. Often used about returning to a job or task you've mastered before.