HAMMERED, AGAIN; Florida shop does tuning the right way.(News)

Byline: STEVEN COLE SMITH

Sometimes,'' says Hartmut Feyhl, "I am a little ashamed to call myself a tuner.'' Not because the calling itself isn't noble (how can making cars go faster and handle better be otherwise?), but because so many cable TV shows use "tuner'' to describe most anyone who lowers a suspension using Home Depot C-clamps, or enhances noise, not performance, by bolting on a big, loud tailpipe extension. "So many of them are parts installers, not tuners,'' Feyhl says. "It has become almost a joke.''

There's nothing funny about the performance or the price of Feyhl's tuner cars. As president and CEO of Renntech, the Florida company that since 1989 has been among the country's top Mercedes tuners, Feyhl has a reputation for dogged attention to detail. Renntech modifications typically have the look and feel of a factory installation, not surprising since Feyhl's childhood home in Germany was located next to the AMG factory, and he apprenticed at the best-known Mercedes mod shop when he was a teenager. By 1986 he had become the technical director of AMG's North American distributorship, where he built the brutally fast AMG Hammer sedan, a 300E with the weak-willed six-cylinder surgically removed and replaced by a much-massaged 32-valve V8.

Renntech first came to our attention more than 13 years ago ("Hammering It Home,'' Jan. 11, 1993), when we wrote about the company's 600E, essentially a 400E with the engine balanced, bored and stroked to 6.0 liters, bumping horsepower from 275 to 385. "Think of it as a second-generation Hammer,'' the story said, "taking advantage of Mercedes design improvements since the AMG original.''

Speaking of design improvements: We made a trip to the Renntech shop, north of Miami, to sample a Mercedes CLS55 Renntech. We've gone on record as more than impressed by the looks and performance of the chance-taking CLS, and more of a good thing is, well, a better thing. The CLS55 AMG's 5.5- liter V8 starts with a healthy 469 hp-which, incidentally, Feyhl says is maybe 25 hp fewer than the engine actually puts out-and Renntech's modifications can take that horsepower to about 650.

Those mods include huge but sanitary top-mounted twin intercoolers, an ECU upgrade, a bigger throttle body and crankshaft pulley kit, and stainless-steel headers. A new carbon fiber engine cover air box had not been fitted to the test car, the final touch of the $37,600 package. Without that piece, the supercharger whine and air intake were louder than Feyhl likes, but we thought it had a nice, means-business sound. The engine's bottom end, Feyhl says, is plenty strong enough to handle the extra ...