Smart ForFour
The 1.5L four-cylinder from Mitsubishi comes as a standard version (80 kW) and as a Brabus variant (up to 130 kW with turbo). The standard version is reliable; the Brabus version is sporty but puts the drivetrain and clutch under considerable strain.
Pocket rocket with four seats
177 hp Brabus turbo, 0–100 in 6.9 seconds, 221 km/h top speed. A four-seat city car with genuine sports car performance — the most surprising fun car of the generation.
Engine Weaknesses 4
Moisture enters the plastic housing of the electronic wastegate actuator. Green corrosion on the contacts and broken teeth on the crown gear prevent the valve from closing — no boost pressure.
Symptoms: Yellow engine warning light, no boost pressure, severe power loss, limp mode, sometimes limited to 30 km/h
Some turbochargers fail completely at very low mileage. Workshop diagnoses a faulty turbo; official replacement costs around €2,500 at a Smart dealer.
Symptoms: No throttle response, complete power loss, engine warning light, strong whistling/whining from the turbo area
The 6-speed dual-clutch gearbox (Twinamic) shifts harshly and judders on engagement. Crawling in 2nd gear is particularly hard on the clutch as it slips continuously.
Symptoms: Harsh shifting, juddering on pull-away, vibrations at low speeds, clutch smell in stop-and-go traffic
Identical to the naturally aspirated version: the thin sheet-metal sump is only bonded with sealant. From 40–60 k km the seal leaks. The sump must be replaced during repair.
Symptoms: Oil patches under the vehicle, oil-coated sump, visible oil film on the sump underside
Vehicle Weaknesses 10
The electric power steering of the ForFour 454 is a known weak point. It fails sporadically or permanently; the steering suddenly becomes heavy. A full steering rack replacement is expensive. Partial repairs are possible.
The sills and wheel arch edges of the ForFour 454 are regularly affected by rust on older vehicles, as stone chips and moisture attack quickly. Frequent city use and lack of underbody maintenance accelerate the problem.
The rear shock absorbers of the ForFour 454 are considered a weak point and sometimes need replacing before 70,000 km. Poor damping has been documented in forums at as little as 66,700 km. Rear-wheel drive variants are particularly affected.
The ForFour 454 brake discs warp due to frequent short-trip use where the brakes never fully warm up and cool down without being allowed to spin freely. Rust spots and heat marks are also common.
Due to the typical short-trip city use, the ForFour 454 battery never fully charges and sulphates prematurely. Combined with the high current draw of modern electronics, batteries fail significantly earlier than in other vehicle types.
The electric window regulators of the ForFour 454 fail due to defective motors, broken cables or faulty switch contacts. Both front and rear window regulators are affected. The tailgate button is also a known problem.
The gear linkage of the manually shifted ForFour 454 is very stiff in cold temperatures, particularly when engaging 5th gear and reverse. The linkage needs lubrication; worn shift joints are a frequent cause.
The ForFour 454 exhaust system rusts primarily at the rear silencer due to typical short-trip city use. Condensation water collects in the silencer and corrodes the steel from the inside. A complete replacement can be due before 80,000 km.
The ForFour 454 AC condenser gets damaged by stone chips and corrosion, leading to refrigerant loss. The AC then no longer cools properly or at all. Compressor wear from insufficient lubrication at low refrigerant levels is also a common consequence.
Plastic trim panels in the ForFour 454 interior work loose over time and cause creaking and rattling noises while driving. Dashboard, door panels and rear covers are particularly affected. Typical age-related phenomenon.