Problems With the SMG M3

Written by erik devaney
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In 2002, the German automobile manufacturer BMW released the SMG M3. An alternative to the standard, high-performance manual-transmission M3, which comes in convertible, sedan and coupe body styles, the SMG M3 offers BMWs patented Sequential Manual Gearbox, or SMG, technology. The technology allows SMG M3 drivers to choose between using an automated transmission mode and a manual transmission mode. However, as a result of this technology, the SMG M3 has several problems.

Unusual Operation

The BMW SMG M3 utilises the same basic transmission and clutch components as the standard BMW M3. However, instead of relying on conventional actuators for these components, the MSG M3 utilises an electrohydraulic control system, or a system that utilises electricity and pressurised fluids to create power. As a result of this advanced actuation system, the MSC M3 does not need -- or have -- a clutch pedal or a conventional lever for shifting gears. When you are driving an SMG M3 in manual mode, you upshift or downshift using specialised paddles on the left and right side of the steering wheel or by using a complex switch in the centre console. As "Car and Driver" magazine notes, this switch, or "stubby shift lever" has a logic that seems backward, as you must push it forward to downshift and push it backward to upshift. For a driver that is accustomed to driving a car with a standard manual transmission, driving the SMG M3 in its manual mode can be confusing.

Automated Mode

When using the BMW SMG M3's automated transmission mode, there is no need to fiddle with paddles and switches. Instead, the car automatically upshifts and downshifts in response to your driving. However, as "European Car" magazine notes, the SMG M3's automated transmission mode does not deliver the same performance as an actual automatic transmission. When upshifting in the automated mode, the SMG M3 lurches as the clutch disengages and there is a noticeable pause before the shifting is complete. When downshifting, the car's engine typically does not provide sufficient RPMs, resulting in a another lurch as the clutch engages. While similar lurching issues can occur when driving the SMG M3 in manual mode, in automated mode they occur without warning, as you do not manually initiate gear levers.

Driving Environment Limitations

The majority of the BMW SMG M3's transmission issues, specifically the lurching and pausing between shifts, occur when driving at low speeds. For this reason, the car is not ideal for driving in urban or densely populated areas, or in other areas that require constant starting and stopping. As "European Car" states, "Around town, the [SMG] M3 can have a slightly notchy throw and jerky clutch engagement."

High Speed Concerns

The BMW SMG M3 performs best at high speeds, such as when driving on highways and other open roads. However, there are two high-speed problems that can potentially occur with the car. First, the SMG M3 will sometimes ignore user inputs in manual mode. So if you try to downshift too early, the car will not complete the task nor will it store the command. In addition, when you make tight turns at high speeds, the shifting paddles on the car's steering wheel, can become inverted, making it easy to accidentally upshift when you meant to downshift or vice versa.

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