Smart Fortwo II (451) (2007 – 2014)

Reliability score : 4.8/10

The second-generation Smart Fortwo (code name W451) succeeds the W450, growing by 19 cm to improve safety (crash tests) and comfort. It abandons Mercedes-Benz petrol engines for 1.0L 3-cylinder blocks of Mitsubishi origin (3B2 family), but retains a Mercedes-Benz diesel engine (OM660), which is the focus of this report. This 0.8 cdi block holds the title of the smallest mass-produced diesel engine in the world. While the Tridion safety cell remains a benchmark, the overall reliability of the 451 is marred by poor statistics: ADAC notes a breakdown rate of 4.1/1000 vehicles/year (below average), the TÜV Report points to a 3-year defect rate of 21.5% (among the worst in the segment), and What Car? gives it a reliability rating of 2/5 (35% breakdown rate over 12 months). The automated gearbox

Common issues

Dysfonctionnement de l'actuateur d'embrayage / boîte de vitesses (AMT) High

🔧 80 000 – 150 000 km

💶 600 – 1 200 €

Vérifier les passages de vitesses et l'absence de bruits anormaux lors de l'essai.

Encrassement ou défaillance de la vanne EGR Medium

🔧 70 000 – 120 000 km

💶 250 – 500 €

Privilégier les trajets plus longs et réguliers pour limiter l'encrassement.

Défaillance du turbocompresseur High

🔧 120 000 – 200 000 km

💶 800 – 1 500 €

Respecter les vidanges et laisser le moteur refroidir avant de couper le contact.

Problèmes d'injecteurs diesel Medium

🔧 100 000 – 180 000 km

💶 400 – 800 € (pour un ou deux injecteurs)

Utiliser du carburant de qualité et un additif nettoyant injecteurs occasionnellement.

Estimated maintenance costs

Oil change	£70 – 130
Timing chain	£650 – 1 200
Clutch	£750 – 1 400
Complete brakes	£220 – 480
Estimated annual budget	£450 – 950

Indicative estimates (independent garage, UK market). Prices vary by region and year.