| Weistec Horsepower | 416 |
| Weistec Torque | 420 |
| Manufacturer | Weistec |
| Street legal in all the US States | No |
| Stock Horsepower | 382 |
| Stock Torque | 391 |
| See more | |
| year | make | model | trim | engine |
|---|---|---|---|---|
| 2010 | Mercedes-Benz | CL500 | Coupe (C216) | 5.5L V8 (M273) |
| 2009 | Mercedes-Benz | CL500 | Coupe (C216) | 5.5L V8 (M273) |
| 2008 | Mercedes-Benz | CL500 | Coupe (C216) | 5.5L V8 (M273) |
| 2007 | Mercedes-Benz | CL500 | Coupe (C216) | 5.5L V8 (M273) |
| 2006 | Mercedes-Benz | CLK500 | Convertible (A209) | 5.5L V8 (M273) |
| 2005 | Mercedes-Benz | CLK500 | Convertible (A209) | 5.5L V8 (M273) |
| See more | ||||
Product Description
The M273 is the V8 counterpart to the M272, sharing its 90-degree DOHC, four-valve architecture but scaled up to a genuinely substantial 5.5 liters. Mercedes introduced it to replace the M113 V8, and it went on to power the brand's flagship naturally-aspirated cars of the era, the S550, E550, CLS550, and their SL and ML equivalents, where smoothness and refinement mattered as much as outright muscle. It stands as the last generation of Mercedes' big, unforced-induction V8 approach before the brand moved on to the downsized, turbocharged M278 and M157, and it's a genuinely impressive piece of engineering in its own right.
Weistec's ECU tune for the M273 recalibrates the factory's ignition, fueling, and torque-management strategy to draw out substantially more of what this 5.5L V8 can do, from 382 to 416 horsepower and 391 to 420 lb-ft in Weistec's own testing. It's a software-only, OEM-level calibration, built with the same validation discipline as Mercedes' own tuning work, with every factory safety system left fully intact, and it takes an already refined, naturally-aspirated flagship V8 to a level Mercedes never calibrated it to reach.
How Do You Get Your M273 ECU Tune Tuned?
Follow these steps — this is what your specific vehicle needs and supports.
Choose Your Tune Stage
Core Improvements
Standard with this tuneFree Add Ons
Pick Your Tuning Method

Cypher Plus
Order a Cypher Plus and tune your car yourself from your phone, entirely through the MyFlasher app. Watch how it works.

Mail It In
Remove your ECU or TCU and mail it to us for tuning. Required for some applications.

In Person
Bring your vehicle, or just your ECU/TCU, to our Anaheim, CA headquarters. Call 714-202-0005 or email sales@weistec.com to schedule.

Cypher Pro Dealer
Visit a certified Cypher Pro Dealer near you. Find one with our dealer locator.
Complete The Upgrade
An ECU tune alone won't remove all factory limits or fix how power reaches the ground. Add these to round out the upgrade with no limitations.
Read the full CPC & TCU breakdown →
What is a CPC module?
The CPC (Central Powertrain Control) is a separate control unit that manages things like the active exhaust valves, radiator fan, intercooler pumps, and speed limiter. On many newer Mercedes-Benz vehicles, it also houses torque limiters that can hold back an ECU tune from reaching its full potential.
What is a TCU tune?
A TCU (transmission control unit) tune delivers faster, firmer shifts with higher line pressure, reducing clutch slip and increasing the transmission's torque capacity. It's a worthwhile upgrade on its own, or paired with an ECU tune for a fully sorted powertrain.
Good to Know
- This is a reflash of your original module, not a stand-alone unit.
- Power gains vary by vehicle, modifications, fuel, and operating conditions (ambient temperature, altitude, etc.).
- New or upgraded spark plugs are always recommended when tuning.
- Product may not be emissions compliant. Check local laws prior to installation.
- Always use a battery charger during programming.

