Smart ForTwo 451 (2007-2014): known problems and buying guide

The clutch and its actuator are the main risk. Check the gear changes first, then the cooling system and the oil level.

Updated 24 October 2026

All versions

Variant	Running cost per month	Median price	Listings	Fuel	Engine codes	Gearbox	Production years
1.0 mhd, 71 PS, 5-speed automated manual, rear-wheel drive Research	€311	€5,900	233	Petrol	3B21	Automatisiertes Schaltgetriebe (5)	2012–2014
1.0 mhd, 61 PS, 5-speed automated manual, rear-wheel drive Research	€312	€5,500	69	Petrol	3B21	Automatisiertes Schaltgetriebe (5)	2012–2014
1.0 mhd, 71 PS, 5-speed automated manual, rear-wheel drive, convertible Research	€303	€6,200	63	Petrol	3B21	Automatisiertes Schaltgetriebe (5)	2012–2015
0.8 cdi, 54 PS, 5-speed automated manual, rear-wheel drive Research	€295	€5,900	54	Diesel	660951	Automatisiertes Schaltgetriebe (5)	2012–2014

Years: built 2007 to 2014 or 2015. Facelifts came in 2010 and 2012.
Most common: clutch and clutch actuator faults on the automated gearbox, and oil loss.
Reliability: 2/5, because the clutch actuator, overheating and oil loss are frequent.
DIY: 2/5, because the engine sits at the rear and a clutch job takes up to a full working day.
Prefer: a car with a clutch job on record and proof that the gearbox was re-learned. Avoid: a car with jerky or refusing gear changes, or coolant loss.

1.0 petrol, 3 cylinders, 61 to 71 PS: the start-stop (mhd) version has the drive belt fault below. No other engine fault confirmed.
1.0 turbo and Brabus, up to about 102 PS: no common fault confirmed.
0.8 CDI diesel, 45 or 54 PS: no engine fault confirmed. The exhaust rusts faster on short trips, especially with this engine.
5-speed automated manual gearbox (one clutch, electric clutch actuator): the main issue on this car. See the first item below.

Issue	Affects	Typical km	Repair cost
Clutch and clutch actuator	Automated gearbox, all 451	Not stated	400-800 EUR (Germany, year not stated)
Overheating and coolant loss	Not split by engine	Not stated	100-1,500 EUR (Germany, year not stated)
Drive belt on MHD petrol	MHD (start-stop) petrol	Not stated	No confirmed price
Oil loss	Not split by engine	Not stated	Not stated
Heater shut-off valve recall	Cars built 2010 to 2014	Not stated	Free (recall)
Exhaust rust	Not split, worst on 0.8 CDI	Not stated	Not stated
Tailgate lock	Not split	Not stated	Not stated

Look for coolant loss. Check the radiator, expansion tank, water pump and hoses for leaks. A leak can mean a water pump or cylinder-head gasket job, which costs up to 1,500 EUR (Germany, year not stated).
Pull away and make several gear changes. Slow, late or jerky shifts, judder, a clutch that slips, a stiff pedal, or the three-bar warning mean a clutch or actuator job, about 400-800 EUR (Germany, year not stated). Ask for proof that the gearbox was re-learned after clutch work. That needs diagnostic equipment.
Check the oil level on the dipstick and look under the engine for oil. Ask for oil change records. Oil loss is common, and it can get the car refused at TÜV.
On an MHD car, listen for whistling, chirping or squealing from the drive belt when starting and driving. These are warning signs of a belt problem.
Look at the exhaust on a lift for rust, mostly on 0.8 CDI cars used for short trips. The catalytic converter and rear silencer are one part on earlier cars, so replacing them is expensive.
Give the VIN to a dealer and ask for open recalls. The heater shut-off valve fix (cars built 2010 to 2014) is free. The brake caliper bracket recall (cars built 28 February to 6 March 2012) corrects bolt torque.

Operational	€142
Workshop	€86
Fixed costs (tax, insurance)	€83
Total per month	€311
New-car depreciation (not included)	€42

ADAC figures for 15,000 km a year over 60 months

Listings on mobile.de priced up to 50,000 EUR, 29 October 2026.

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