Tuning your Mercedes Benz CLK 320 to produce more horsepower and achieve better gas mileage can be done in three important ways. Although each upgrade can be done independently, performing all three at once will maximise the effect of your tune-up. You can install an aftermarket exhaust, which will improve the flow of combusted air out of the engine. Then, you can install an aftermarket cold air intake system that will increase the flow of cool air into the engine relative to the factory air-box. As a finishing touch, you can add a new ECU to optimise the improved air-to-fuel ratios that the exhaust and intake can create.
Replace the factory exhaust system on your CLK 320 with an aftermarket performance exhaust or a custom performance exhaust. These units will offer better flow of combusted air out of the engine and can directly improve horsepower. By creating a less restrictive exhaust, you are increasing the capacity for more air to be drawn into the engine.
Install an aftermarket cold air intake system to replace the factory-equipped, plastic air box and air filter. A cold air intake exposes the air filter directly to the ambient environment, allowing it to draw in colder air as the car moves forward and replacing the air in the air box, which is prone to "heat soak," meaning the air box is continually filled with warmer air because of the engine's operating temperature.
Replace the factory-equipped engine control unit, or ECU, with an aftermarket unit that is designed to work with a performance exhaust and cold air intake. With the addition of the cold air intake and exhaust, your factory ECU will be making constant adjustments to accommodate the changes in airflow. Replacing the factory ECU with an aftermarket unit will essentially give your CLK a custom fuel map for the engine that optimises the new air intake and exhaust ratios, providing the best and most efficient fuel disbursement to compliment the other two upgrades.