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Smart (mcc) Fortwo Cabriolet Problems & Known Issues

The most common Smart (mcc) Fortwo Cabriolet problems ranked by severity — what to watch for, what it costs to fix, and what happens if you ignore it.

Generations

450 — First Generation
2000–2007
0.7 Petrol, 1.0 Petrol
451 — Second Generation
2007–2015
0.7 Petrol, 1.0 Petrol, 1.0 CDI

Top issues to watch for

The most serious Smart (mcc) Fortwo Cabriolet problems ranked by severity. We track 5 known issues — here are the ones you need to know about first.

Dangerous
Brake hose deterioration and failure
450, 4512000–201520k–120k miles
MOT data shows Smart ForTwo cabriolets fail flexible brake hose inspections at 39.3 times the fleet average, primarily affecting 0.7L petrol variants. The brake hoses become excessively damaged, deteriorated, chafed, twisted or stretched at unusually low mileages. This affects the structural integrity of the brake hydraulic system and represents a critical safety risk. The issue appears to be worsening across the tested period 2020-2024.
What happens if ignoredBrake hose failure results in immediate loss of braking ability to the affected wheel or complete hydraulic system failure. This creates an extreme safety risk and the vehicle becomes undriveable. Emergency repair is required immediately. Total brake system failure can occur without warning.
Independent garage
£150–£300
Specialist
£200–£400
Main dealer
£300–£500
Parts only
£40–£80
Dangerous
Brake pipe corrosion
450, 4512000–20150k–120k miles
Smart ForTwo models show brake pipe corrosion and damage at 6.8 times the fleet average according to MOT data. The compact chassis design routes brake lines close to road spray and salt, particularly around rear suspension mounting points. Corroded brake lines represent an extreme safety risk as they can fail suddenly under braking pressure, causing complete brake system failure.
What happens if ignoredBrake line failure causes immediate and total loss of braking ability. This represents an extreme safety risk and the vehicle becomes undriveable instantly. Brake line failure typically occurs without warning and often under maximum braking load when failure consequences are most severe.
Independent garage
£300–£600
Specialist
£400–£700
Main dealer
£500–£900
Parts only
£80–£150
Major
Engine mounting deterioration
450, 4512000–201540k–100k miles
The three-cylinder engines in these cars generate significant vibration that accelerates rubber mount degradation. Failed mounts cause excessive drivetrain movement, gear selection issues, and potential damage to surrounding components.
What happens if ignoredFailed engine mounts cause excessive vibration, premature wear of other components, and potential damage to exhaust system, brake lines, or electrical connections. The car remains driveable but comfort is severely compromised and secondary damage may occur if not repaired promptly.
Independent garage
£200–£400
Specialist
£300–£500
Main dealer
£400–£700
Parts only
£80–£150
Major
Brake caliper binding
450, 4512000–20150k–100k miles
MOT testing reveals Smart ForTwo models show significant brake effort with no brake applied at 19.2 times the fleet average, indicating binding brake calipers. The compact brake system design and exposure to road salt accelerates caliper piston and slider pin corrosion. Binding brakes cause premature pad and disc wear, reduced fuel economy, and potential brake overheating.
What happens if ignoredBinding brakes cause rapid brake component wear, reduced fuel economy, and potential brake fade or fire in extreme cases. The affected brake may overheat and lose effectiveness completely. Immediate repair is required as the condition typically worsens rapidly.
Independent garage
£150–£300
Specialist
£200–£400
Main dealer
£300–£500
Parts only
£50–£120

1 more known issues tracked

Including wear items, electrical niggles, and generation-specific problems.

MOT failure hotspots

Based on DVSA MOT test data. These are the items where the Smart (mcc) Fortwo Cabriolet fails at a significantly higher rate than the average car.

Engine mounting/bracket severely damaged or det...
Bodywork · 20-40k miles
MOT failure rate: 89x the fleet average
Sample: 1,132 tests
Brake hoses perished or damaged
Brakes · 20-40k miles
MOT failure rate: 39x the fleet average
Sample: 1,538 tests
Fuel system leaking, or missing or ineffective ...
Bodywork · 20-40k miles
MOT failure rate: 36x the fleet average
Sample: 859 tests
Emissions failure
Exhaust & Emissions · 40-60k miles
MOT failure rate: 22x the fleet average
Sample: 221 tests
Light unit fault
Lights & Electrics · 20-40k miles
MOT failure rate: 18x the fleet average
Sample: 986 tests
Tyre valve seriously damaged or misaligned
Tyres · 20-40k miles
MOT failure rate: 17x the fleet average
Sample: 1,971 tests

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Related

Smart (mcc) Fortwo Cabriolet reliability FAQs

What are the most common problems with the Smart (mcc) Fortwo Cabriolet?

The Smart (mcc) Fortwo Cabriolet has 5 known issues across 3 severity levels. The most serious are: Brake hose deterioration and failure, Brake pipe corrosion.

Is the Smart (mcc) Fortwo Cabriolet reliable?

The Smart (mcc) Fortwo Cabriolet has 2 dangerous and 2 major known issues. Most can be avoided with a thorough pre-purchase check and full service history.

How much does it cost to fix Smart (mcc) Fortwo Cabriolet problems?

Repair costs range widely. The most significant issue (Brake hose deterioration and failure) costs £150–£300 at an independent garage. Minor issues can be under £200. Always get a full inspection before buying.

Which Smart (mcc) Fortwo Cabriolet generation is most reliable?

The 450 (2000–2007) has the fewest dangerous issues (2). However, condition and service history matter more than generation — a well-maintained earlier car can be more reliable than a neglected newer one.