Smart Fortwo (451)
The second-generation Smart Fortwo (Type 451) addressed many of the original's flaws, offering a slightly longer wheelbase for a marginally better ride and replacing the fragile Mercedes engines with much more robust 1.0-litre Mitsubishi units (both naturally aspirated and turbocharged). In the UK, it remains an exceptional urban commuter, offering decent reliability and incredibly low running costs. The automated manual gearbox is still somewhat slow but vastly improved over the 450. It is the sensible choice for city drivers who want the iconic Smart footprint but need dependable daily reliability.
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Common Faults & Reliability
These are the most common documented problems for the Smart Fortwo (451), sorted by their typical impact and frequency.
MHD Drive Belt Failure
high severityThe Mild Hybrid Drive system uses a belt to start the engine and drive the water pump. If the belt snaps, the engine will overheat almost instantly, often warping the head.
Clutch Actuator Failure
medium severityThe actuator that operates the clutch can seize or wear out, leading to jerky gear changes or failure to select drive.
SAM Unit Corrosion (Water Ingress)
high severityIn the UK, water can enter the cabin via the door seals or heater intake and track down to the SAM unit (located in the passenger footwell).
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