From Zurich-Kloten airport to Thalwil (approx. 30 min.):
Take highway A51 towards Zurich-City, then follow the signs towards Chur/San Bernardino, exit Thalwil 

From Zurich city to Thalwil (approx. 15 min.):
Take highway A3 towards San Bernardino/Chur, continue for approx. 8 km (approx. 5 min.) to exit Thalwil