End of April 1998 was presented at the Turin Motor Show an updated SL model range with newly developed engines and subtly redesigned. The main activities under this facelift included the introduction of the new V-engine generation with six and eight cylinders, which replaced now the SL, the six-cylinder M 104 series and the V8 unit of series M 119th Thanks to three-valve technology and dual ignition consumed the new engines up to ten percent less fuel than the previous models and also distinguished by very low exhaust emissions. The power spectrum ranges from 150 kW (204 hp) in the SL 280 about 165 kW (224 hp) in the SL 320-225 kW (306 hp) in the SL 500. The top model SL 600 decreed to continue the proven twelve-cylinder engine M 120 with 290 kW (394 hp). The SL 60 AMG accounted for as part of the facelift and was no longer available in June 1998th
The design of the SL was only slightly modified; Target of subtle stylistic retouching was to give the sports car a more dynamic appearance. This was achieved through a slightly modified rear section, where present, the now monochromatic cover glasses of taillights with only three bars in a softer shape. A new oval tailpipe of the exhaust system and an adaptation to the bumper underline the sporty appearance. Round shapes dominate even in the new exterior mirrors, which had been adapted to the SLK design and constitute the most important external distinguishing feature of the facelifted models. Door handles and Exterior trim appeared high gloss painted in body color with the new SL models. Modified components include the size and design of the wheels: The facelifted SL models were fitted as standard with newly designed five-hole alloy wheels and tires in size 245/45 ZR 17th
In spri 1999 supplemented two particularly powerful AMG models the type range of 129 series: the SL 55 AMG was equipped with a 260 kW (354 hp) V8 engine equipped while the V12 engine of the SL 73 AMG even 386 kW (525 hp ) mobilized with a maximum torque of 750 Nm. Although the speed of the two top models was also electronically limited to 250 km / h the restriction was requested by the customer, but also be repealed.
In August 1999, the Electronic Stability Program ESP was 320 part of the standard equipment even in the two six-cylinder models SL 280 and SL. Two years later, in July 2001, celebrated the SL 500, the first model of the new SL series R 230 world premiere. In the same month ran at the Bremen plant, the last of a total of 204,940 copies of the R 129 from the tape. Thus, the first built in Bremen SL was in terms of overall volume not quite as successful as its predecessor, the still holds the record with 237,287 vehicles; compared to the average annual production, however, the R 129 is far in the lead with about 16 500 units. Successful model of the R 129 series was the equipped with the four-valve V8 engine M 119 5-liter variant, originated from between 1988 and 1998, a total 79 827 copies. The rarest by far was exemplary of the SL 280 with a V6 engine, which functioned as an entry model in the range from 1998 to 1704 only once left the production line.