The six-cylinder SL400 and later SL450 are described by their owners as quick enough, quiet, comfortable, reliable and 'slept on,' with the all-aluminum construction cited as making them the pick of the SL litter. At least one owner claims a mild modification made his SL400 quicker than a friend's SL550.
SL400 / SL450 V6 variants: underrated and reliable
Mercedes-Benz SL (R231) · driving