Smart Roadster horsepower depends on the variant: the Lite produces 61hp (45kW), the standard 60kW makes 82hp, the Brabus SB2 delivers 90hp (66kW), and the full Brabus tops out at 101hp (74kW). All figures come from the same 698cc turbocharged three-cylinder engine, differing only in boost pressure and ECU calibration.
Those numbers tell only half the story. Spec sheets list peak power at the flywheel under ideal conditions, but real-world dyno runs, the effect of turbo efficiency at different boost levels, and the genuine ceiling imposed by the Garrett 1238S compressor map paint a much richer picture. This article walks through every factory variant, explains precisely why the power differs between them, examines what a professional remap can add safely, and sets honest expectations for anyone contemplating more ambitious hardware modifications. Whether you own a base Lite or a full Brabus, understanding your engine’s real potential prevents expensive mistakes.
Smart Roadster Horsepower by Variant: What the Factory Actually Built
Smart produced the 452 Roadster between 2003 and 2006 in four distinct power outputs, all sharing the same Mitsubishi-derived 698cc inline three-cylinder turbocharged block. The differences between them are almost entirely software and boost-related, which is exactly why remapping is so effective on this platform.
The 45kW Lite (61hp) is the one to avoid for enthusiast use. It runs 0.89 bar of boost and, crucially, was built without an oil cooler for the turbo — a cost-cutting measure that significantly limits thermal headroom and long-term reliability under sustained load.
The 60kW standard (82hp) is the most common variant and, for most owners, the best all-rounder. It runs 1.09 bar, has the oil cooler fitted, and represents a sensible starting point for tuning. The 66kW Brabus SB2 (90hp) pushes boost to 1.33 bar and adds revised ignition timing. The full 74kW Brabus (101hp) runs 1.43 bar and is the most sorted factory calibration, though it puts the 1238S closer to its efficiency island limits.
Why the Same Engine Makes Four Different Power Levels
Understanding smart roadster bhp differences between variants requires a brief look at how the Bosch MEG 1.1 ECU controls the engine. The MEG 1.1 governs boost pressure via a pneumatic wastegate actuator on the Garrett 1238S. Turn up the reference pressure and the wastegate stays closed longer, allowing the turbo to build more boost before bleeding off. That alone accounts for the bulk of the power difference between a 61hp Lite and a 101hp Brabus.
Ignition timing is the second lever. More boost means more cylinder pressure, which increases knock risk. The SB2 and Brabus maps carry more aggressive advance curves, which is why knock and pre-ignition are the real limiting factor when tuners try to push beyond 1.43 bar on pump fuel. Fuel delivery is adjusted accordingly, but the injector sizing remains constant across all variants — a relevant constraint at the very top of the power range.
There is also a torque management layer built into the standard and Lite maps specifically to protect the Softouch gearbox. The Brabus calibrations relax this slightly, which is one reason Brabus cars feel more responsive in mid-range pulls. It is also why the stock clutch becomes the limiting component when torque exceeds roughly 200Nm under aggressive tuning.
What the Garrett 1238S Can Actually Deliver
Every smart roadster horsepower discussion eventually circles back to the turbocharger. The 1238S is a small fixed-geometry unit with a pneumatic wastegate — excellent for spool characteristics on a 698cc engine, but physically bounded by its compressor map. At the boost levels the factory Brabus map requests (1.43 bar), the compressor is already operating near the edge of its efficiency island.
Push beyond that without hardware changes and you enter a region of rising inlet temperatures, compressor surge risk, and diminishing power returns. Our detailed analysis of where the 1238S sits on its compressor map shows that the unit can support approximately 110–115hp at the flywheel before thermal and surge concerns become significant. Beyond that, a turbo upgrade is not optional — it is the only responsible path.
Exhaust flow is also a genuine constraint. The standard backpressure restricts charge scavenging at higher revs, and a properly sized exhaust upgrade measurably reduces backpressure, improving turbo efficiency and extending the usable rev range without changing boost pressure at all.
BOOST BY VARIANT
Factory Boost Pressures Determine Smart Roadster Horsepower
All four variants use the same 698cc turbo engine. The power difference is almost entirely boost and timing calibration.
- Lite 45kW — 0.89 bar, no oil cooler, 61hp
- Standard 60kW — 1.09 bar, oil cooler fitted, 82hp
- Brabus SB2 66kW — 1.33 bar, revised timing, 90hp
- Full Brabus 74kW — 1.43 bar, most aggressive factory tune, 101hp
Real Dyno Gains from a Smart Roadster Remap
A professional remap on the 60kW standard variant is consistently the most cost-effective modification available for this car. On the dyno, a well-executed Stage 1 map on a healthy standard engine with a fresh air filter and no hardware changes typically returns 88–95hp at the wheels, depending on conditions and the individual engine. That equates to roughly 100–108hp at the flywheel — a 25–30% improvement over the 82hp factory figure.
The torque gain is arguably more useful in daily driving. Whereas the factory 60kW map produces around 100Nm peak, a competent remap will push this to 135–145Nm, entirely transforming the mid-range flexibility that makes the car feel alive on B-roads. What a Stage 1 remap actually delivers on a standard 60kW car is covered in thorough detail in our guide to Stage 1 power gains, including real before-and-after dyno plots.
Starting from a Brabus 74kW, the remap headroom is smaller because the factory calibration is already aggressive. Gains of 8–12hp at the flywheel are typical — useful, but not transformative. The hardware is the bottleneck at that point.
Safe Limits for the 698cc Turbo Engine
The 698cc block is robust within its intended parameters, but it rewards respect. The main mechanical limits are head gasket integrity above approximately 1.55 bar of sustained boost, piston crown temperatures at very high advance settings, and oil supply to the turbo bearing. The Lite’s absence of an oil cooler is relevant here – tuning a Lite without addressing cooling is genuinely risky.
On a standard or Brabus car with the oil cooler present and the cooling system in good order, 110hp at the flywheel via remapping alone is achievable without dramatically shortening engine life. Beyond that, you need the hardware to match: a uprated turbocharger is required to make power above 115hp reliably, and the thermal envelope of the 1238S under sustained high-boost conditions must be understood before pushing further. Exhaust gas temperature is the key metric to watch — the relationship between EGT, timing, and turbo longevity is nuanced enough that it deserves its own study.
Fuel quality matters more than many owners appreciate. The knock-limited ignition maps on the Brabus calibrations were developed on 98RON fuel in controlled conditions. Running a heavily remapped car on 95RON will cause the ECU to retard timing under load, blunting power gains and increasing heat. Always use premium fuel on any remapped 452.
Smart Roadster Top Speed and How Power Relates to It
Smart roadster top speed is electronically limited to 135 km/h (84 mph) on the standard 60kW and most Brabus variants — a decision Smart made to protect the Softouch gearbox and keep insurance categories reasonable. The limiter is active in the ECU map and can be adjusted during a remap. Without the limiter, a remapped 60kW car with a free-flowing exhaust is typically capable of 145–150 km/h, and a properly tuned Brabus or Stage 2 setup can approach 160 km/h, depending on gearing and aerodynamic drag.
It is worth noting that the Roadster’s aerodynamics are reasonably efficient for a car of its era, with a drag coefficient of around 0.38 Cd. The lightweight kerb weight — typically 790–820kg depending on specification — means that even the 82hp standard variant achieves a power-to-weight ratio better than many contemporary hot hatches. Smart roadster top speed figures from spec sites often reflect the limited value rather than the car’s true aerodynamic ceiling, which is an important distinction for prospective tuners.
Frequently Asked Questions
How much horsepower does a standard Smart Roadster have?
The standard 60kW Smart Roadster produces 82hp (61kW at the flywheel) in factory form. The entry-level Lite variant makes 61hp (45kW), while the Brabus SB2 and full Brabus produce 90hp and 101hp respectively. All variants use the same 698cc turbocharged three-cylinder engine.
Can you get 100hp from a remapped standard Smart Roadster?
Yes. A professional remap on a healthy 60kW engine regularly produces 100–108hp at the flywheel, typically around 88–95hp measured at the wheels on a hub dyno. The Garrett 1238S turbocharger comfortably supports this power level without hardware modifications, provided the engine is in good mechanical condition.
What is the Smart Roadster top speed without the limiter?
The factory limiter is set to 135 km/h (84 mph). With the limiter removed via a remap, a standard 60kW car typically reaches 145–150 km/h. A remapped Brabus or a car with a turbo upgrade can approach 155–160 km/h depending on conditions, gearing, and aerodynamic drag.
Is the Smart Roadster Lite worth buying for tuning?
Generally no. The Lite lacks the oil cooler fitted to all higher-power variants, which limits its thermal headroom significantly under boost. For tuning purposes, always start with the 60kW standard or a Brabus variant. The cost of retrofitting an oil cooler usually negates any price advantage the Lite offers.
