ABOUT US
RENNtech has become the premier Mercedes-Benz specialist and Hartmut Feyhl himself is regarded by many as USA’s foremost authority in Mercedes tuning.
His vast experience comes from 12 years spent at AMG Germany before serving as the North American division’s Technical Director. Prior to the tuning company’s merger with Mercedes-Benz in 1989, by the request of AMG Germany, Feyhl branched out on his own to start RENNtech and service the existing AMG North America customers.
Hartmut Feyhl President & Founder RENNtech, Inc.
Performance without compromise - this is the foundation upon which we have built our reputation. Established in 1989 by Hartmut Feyhl, RENNtech has evolved and grown from servicing AMG’s customers into the foremost authority on tuning and customizing AMGs and Mercedes-Benz. RENNtech also offers tuning solutions for Porsche, Audi and Bentley vehicles, along with other European luxury cars. Over the years, we have developed high-performance products for virtually all Mercedes-Benz AMG vehicles. Some of the most notable among these are the 200 mph RENNtech E7.4RS (which claimed ‘Fastest Sedan in the World’ honors by Car and Driver Magazine in 1996) and the most recent Mercedes-AMG GT63 RIIIx with close to 1200 HP. Each of these vehicles are just a sampling of what RENNtech has achieved - featuring extreme performance, upgraded aesthetics and a fit and finish that rivals factory vehicles.
Frequently asked questions
Why isn't the factory ECU tuned like RENNtech's?
Manufacturers prioritize emissions, fuel economy, regulations, drivability, and marketing strategy over performance. RENNtech tunes optimize ignition, throttle, fuel, boost, and rev limits for maximum performance without compromising safety.
Is the ECU upgrade plug-and-play?
Yes. Just replace the stock ECU with the RENNtech-tuned unit. Connectors are foolproof, and live tech support is available.
Does RENNtech remove the speed limiter?
Yes, raised to the safe MB-recommended top speed based on tire rating.
What's the ECU turnaround time?
Typically one business day. Units received in the morning often ship back the same day.
How do I send in my ECU?
If a “bench flash” needs to be performed please request ECU removal instructions, fill out the ECU info form, and ship to RENNtech with sufficient insurance.
Ship to:
RENNtech, Inc.
Att: ECU Tuning
7825 SW Ellipse Way
Stuart, FL 34996
Do I get the same ECU back?
Yes, each ECU is “married” to its vehicle and cannot be exchanged.
Why trust RENNtech?
RENNtech parts are designed to work with factory systems, backed by warranty, and trusted by Mercedes-Benz dealerships. Our goal is to deliver reliable performance without compromising safety or drivability.
Will dealer service reset the tune?
Dealer software updates can overwrite the tune. RENNtech will reflash with the latest file at no charge (customer covers shipping). Please send HHT tuner along with original packaging and receipt, contact information and return address.
Do added performance parts require re-tuning?
Minor bolt-ons (airbox, mufflers) don’t. Major exhaust/boost upgrades do require reprogramming.
Will aftermarket parts void my warranty?
Under the Magnuson-Moss Warranty Act, a warranty cannot be denied just for using aftermarket parts. Only claims directly caused by aftermarket parts may be denied.
RENNtech DLM Troubleshooting
- Settings not applying: Ensure drivers are installed.
- Rear lifts when front lowers: Adjust “Channel Polarity” in software.
- Airmatic/ABC malfunction: Vehicle lowered too much; reset to recommended settings.
- Car returns to stock height at ~30mph: Normal; adjust “Speed Settings” if desired.
Career Opportunities
Join Our Team
RENNtech is always looking for talented individuals with experience to be a part of the team. Those interested, please send the position applying for in the subject line with a detailed resume to: info@renntechmercedes.com
Note: Due to the high volume of resumes we receive, we're not able reply to each application. This does not mean we did not receive it, all resumes are kept on file and qualified candidates are contacted as positions are available
