Smart Roadster
The 0.7L version of the Suprex three-cylinder is a development of the 0.6L with more displacement and better torque. In the Roadster it provides adequate driving fun. The known weaknesses of the 0.6L were improved; turbo problems occur less frequently.
Little corner carver
Only 61 hp, but 790 kg, low centre of gravity and a mid-engine layout. Surprisingly lively on country roads — even the base version delivers real roadster feel.
Engine Weaknesses 4
The ball joint between the actuator and wastegate flap seizes with rust. The flap can no longer open, boost pressure goes unregulated. Engine enters limp mode.
Symptoms: Engine enters limp mode, no power above 3,500 rpm, engine warning light, feels throttled
The oil feed and return lines to the turbocharger become blocked by carbon sludge. The turbo runs dry and is replaced repeatedly, even though the root cause lies in the oil lines.
Symptoms: Whistling noises from the turbocharger, power loss, increased oil consumption, turbo failure
The M160E7 tends to lose oil from various seals. Regularly flagged at the MOT. Short-trip use makes the problem worse through oil dilution.
Symptoms: Oil patches under the vehicle, oil smell from engine bay, dropping oil level, MOT advisories for oil leaks
The automated 6-speed gearbox of the 450 shifts harshly and with a jerk. The clutch actuator wears out, especially when exposed to moisture and contamination.
Symptoms: Juddering on gear changes, delayed gear selection, gearbox refuses to shift to the next gear
Vehicle Weaknesses 12
The SAM unit (control module for fuses and actuators) sits in the driver's footwell and is damaged by water ingress through unsealed body seams and the tray seal. Capacitors and circuit tracks are destroyed; repair is expensive.
The Roadster 452 suffers from systematic water ingress through mirror triangle seals, roof rails and incompletely sealed body seams. Water flows along cables directly into the SAM. Particularly prominent on the cabriolet variant.
The Roadster's roof rails rust under the rubber seals without being immediately visible from the outside. Small rust spots on the rubber seal usually indicate advanced corrosion underneath. Sills are also affected.
The brake hoses age and can swell internally, restricting brake fluid flow. The Roadster has comparatively small brakes for its performance, and porous hoses significantly increase the safety risk.
Various sensors on the Roadster are failure-prone, including the camshaft sensor and throttle position sensor. Water ingress into ECU housings or vibration damage is often the cause. Leads to sporadic engine shutdowns while driving.
The electrohydraulic roof mechanism is failure-prone. Broken drive cables, corroded guide rails and worn locks prevent the roof from opening or closing correctly. Spare parts are now hard to find and expensive.
The semi-automatic sequential gearbox of the Roadster shows significant weaknesses when pulling away and produces a noticeably long shift pause when changing from 3rd to 4th gear. The gearbox wiring harness can chafe through, causing corroded connector contacts.
The rubber bushings in the front and rear control arms wear and need replacing. Polyurethane replacement bushings are a popular upgrade. Original bushings must be removed by burning or drilling out.
The side window seals shrink over time and allow water to enter along the window edge, running toward the carpet and SAM. Particularly on vehicles over 10 years old, this is a frequently overlooked water entry point.
The rear section of the Roadster is particularly rust-prone due to the rear engine mounting and the vehicle's proximity to the road surface. Spray water and condensation attack the metal parts at the rear. Regular underbody inspection is strongly recommended.
The complex folding sliding roof of the Roadster 452 has a high failure rate. Cables snap, hinges and side rails bend, tension cable springs fatigue.
On the Roadster 452, water enters at several points: at the B-pillar where the soft top meets the roll bar, at the side window seals, and through faulty channel seals in the footwell.