Smart Roadster 452
Weaknesses, engine ratings and buying advice
The smart Roadster 452 (2003–2006) was the attempt to turn smart hardware into a tiny sports car – low, light (under 800 kg), with a mid-engine layout and rear-wheel drive, offered as an open Roadster or as a Roadster-Coupé with a glass roof. It is powered by the 0.7-litre three-cylinder turbo (M160E7) with 60 kW, or 74/80 kW in the Brabus-tuned version. The appeal lies in the go-kart-like handling, the low seating position and the high fun factor at modest speeds – it is not fast, but extremely agile. Notorious and decisive when buying is water ingress: leaking roof seals, blocked water drains and porous seals on the targa roof and rear lead to wet footwells, soaked carpets and, as a consequence, electrical damage to the control module (SAM) under the passenger seat – a common and costly follow-on failure. Add to that the typical smart jerky automated gearbox, turbo actuator problems and the general fragility of many attached parts. A Roadster without documented drying-out and a checked SAM is a risk. The electric windows, the roof mechanism and the fragile door handles also cause age-related trouble. When buying, it is worth looking under the carpets and into the spare-wheel well: standing water or water marks are a clear warning sign. A car kept dry, electrically faultless and with evidence of resealed roof gaskets is the only sensible choice. Because of the low build numbers (around 43,000 made) and its cult status, the 452 is now a collector's item: well-kept, garage-stored Brabus coupés fetch 8,000–15,000 euros, plain roadsters less, with values stable to rising. Anyone who wants driving fun and brings the maintenance discipline gets a unique car with character – anyone after a reliable daily driver is looking in the wrong place. As a second or fair-weather car with a trusted workshop, however, it is a gem that barely loses value.
Engine Overview
The Smart Roadster 452 is available with 3 engine variants — from 61 to 101 hp.
The 0.7-litre evolution of the Suprex three-cylinder adds noticeable displacement and torque, making mid-range power delivery feel smoother. The turbocharging provides decent pull but requires clean charge-air routing and an intact wastegate. Several weaknesses of the early 0.6 version were addressed, yet age-related issues with ignition coils, charge-air hoses and the turbo actuator remain typical. A well-maintained cooling system and regular oil changes are key at purchase, because thermal load in the rear stays high.
- !! Wastegate linkage corrodes and sticks from 70,000 km
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 - !! Turbocharger oil supply blocked from 90,000 km
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 - !! Excessive oil loss from the engine from 80,000 km
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
+ 1 more engine weaknesses + vehicle weaknesses
The 0.7-litre evolution of the Suprex three-cylinder adds noticeable displacement and torque, making mid-range power delivery feel smoother. The turbocharging provides decent pull but requires clean charge-air routing and an intact wastegate. Several weaknesses of the early 0.6 version were addressed, yet age-related issues with ignition coils, charge-air hoses and the turbo actuator remain typical. A well-maintained cooling system and regular oil changes are key at purchase, because thermal load in the rear stays high.
- !! Wastegate linkage corrodes and sticks from 70,000 km
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 - !! Turbocharger oil supply blocked from 90,000 km
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 - !! Excessive oil loss from the engine from 80,000 km
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
+ 1 more engine weaknesses + vehicle weaknesses
The 0.7-litre evolution of the Suprex three-cylinder adds noticeable displacement and torque, making mid-range power delivery feel smoother. The turbocharging provides decent pull but requires clean charge-air routing and an intact wastegate. Several weaknesses of the early 0.6 version were addressed, yet age-related issues with ignition coils, charge-air hoses and the turbo actuator remain typical. A well-maintained cooling system and regular oil changes are key at purchase, because thermal load in the rear stays high.
- !! Wastegate linkage corrodes and sticks from 70,000 km
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 - !! Turbocharger oil supply blocked from 90,000 km
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 - !! Excessive oil loss from the engine from 80,000 km
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
+ 1 more engine weaknesses + vehicle weaknesses
Vehicle Weaknesses
| Weakness | Cost | |
|---|---|---|
| SAM Unit Destroyed by Water Ingress 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. Symptoms: Indicators flashing erratically, wipers fail, vehicle does not start, complete electrical failure from 70,000 km | Medium | |
| Sensor Failures (Camshaft Sensor, Throttle Position Sensor) 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. Symptoms: Engine cuts out while driving, engine warning light, irregular idle, limp mode from 70,000 km | Low |
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Explore more
All Smart models Known Problems and Issues +
A total of 17 weaknesses have been documented for the Smart Roadster 452 (2003–2007) — 4 engine-related and 13 vehicle-related. One problem engine: M160E7 (0.7L Turbo). Typical issues affect Electronics, Body, Rust, Gearbox.
Roadster (M160E7, 2003–2005) — Stay Away!: Wastegate linkage corrodes and sticks, Turbocharger oil supply blocked, Excessive oil loss from the engine. Power: 61 PS.
Roadster (M160E7, 2003–2005) — Stay Away!: Wastegate linkage corrodes and sticks, Turbocharger oil supply blocked, Excessive oil loss from the engine. Power: 82 PS.
Roadster (M160E7, 2003–2005) — Stay Away!: Wastegate linkage corrodes and sticks, Turbocharger oil supply blocked, Excessive oil loss from the engine. Power: 101 PS.
What to watch out for with the Smart Roadster? See the detailed listing of all engine and vehicle weaknesses in the sections above.
Frequently Asked Questions
What problems and weaknesses does the Smart Roadster 452 have? +
What should I look for when buying a used Smart Roadster 452? +
Which engine is recommended? +
Which Smart Roadster 452 engine is the most fun? +
Is the Smart Roadster 452 worth buying used? +
What horsepower variants are available for the Smart Roadster 452? +
Last updated: February 2026 · All information without guarantee