The Polestar B525 is a 1,969 cc, inline‑four turbocharged petrol engine, often integrated into a mild — hybrid system, produced from 2022 for Polestar's performance — oriented models. It features a twin — scroll turbocharger, direct fuel injection, and a 48V mild — hybrid system (BAS) to enhance responsiveness and efficiency. The engine delivers a robust 350 kW (476 PS) and 540 Nm of torque, with the mild — hybrid system providing an additional power boost for overtaking.
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All production years (2022–Present) meet Euro 6d emissions standards .
The Polestar B525 is a 1,969 cc inline‑four turbocharged petrol engine, often paired with a 48V mild-hybrid system, engineered for premium SUVs (2022-Present). It combines a twin-scroll turbocharger with direct injection and hybrid assist to deliver exhilarating acceleration and enhanced low-end responsiveness. Designed to meet Euro 6d standards, it balances high performance with regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,969 cc | |
Fuel type | Petrol (95 RON min.) | |
Configuration | Inline‑4, DOHC, 16‑valve | |
Aspiration | Twin-scroll turbocharged | |
Bore × stroke | 82.0 mm × 93.2 mm | |
Power output | 350 kW (476 PS) | |
Torque | 540 Nm @ 2,000–5,400 rpm | |
Fuel system | High-pressure direct injection (Bosch) | |
Emissions standard | Euro 6d | |
Compression ratio | 10.5:1 | |
Cooling system | Water‑cooled | |
Turbocharger | Twin-scroll (Garrett) | |
Timing system | Chain-driven | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 187 kg (incl. mild-hybrid components) |
The Polestar B525 was developed for Polestar's P3 platform with longitudinal mounting. This engine features platform-specific adaptations-integrated mounting for the 48V mild-hybrid starter-generator and revised cooling for the twin-scroll turbo-and is currently exclusive to the Polestar 3. All adaptations are documented in OEM technical bulletins.
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The B525's primary documented area of focus is potential carbon buildup on intake valves, with elevated incidence in vehicles subjected to frequent short trips. Polestar SIB PST-001 recommends proactive inspection, while owner feedback indicates this is a manageable characteristic rather than a widespread failure. Urban driving cycles increase deposit formation, making adherence to recommended fuel quality and occasional higher-RPM operation beneficial.
Analysis derived from Polestar technical bulletins (2022-2024) and aggregated European owner feedback (2023-2024). Repair procedures should follow manufacturer guidelines.
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Based on its Volvo B5 engine lineage and early data, the B525 is expected to be robust with proper care. The main long-term consideration is managing intake valve carbon buildup through driving habits or periodic cleaning. Using the correct 0W-20 oil and premium fuel is essential for longevity.
The most frequently noted issues are potential carbon buildup on intake valves and occasional 48V mild-hybrid system fault codes. Coolant leaks from the thermostat housing, inherited from Volvo B5 engines, are also a known possibility. These are generally manageable with proper maintenance.
As of now, the B525 engine is used exclusively in the Polestar 3 SUV, specifically in the 'Dual Motor Performance Pack' variant. It is not found in the Polestar 2 or any Volvo models in this specific high-output, hybrid configuration.
Aftermarket ECU tuning is common on the B525 platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.
Official WLTP combined figures for the Polestar 3 with the B525 are around 1.4 L/100km (electric) and 7.4 L/100km (petrol-only). Real-world petrol consumption typically ranges from 9.5 to 12.5 L/100km (23-28 mpg UK) depending heavily on driving style and use of electric mode.
Yes. Like virtually all modern DOHC engines, the B525 is an interference design. If the timing chain were to fail, the pistons would collide with the open valves, causing catastrophic internal engine damage. Fortunately, the chain is designed for the engine's lifetime.
Polestar mandates the use of 0W-20 engine oil meeting their specific VCC RBS0-2AE standard. This low-viscosity oil is crucial for the engine's efficiency, turbocharger protection, and the operation of the variable valve timing system. Using the wrong oil can cause damage.
Comprehensive technical documentation and regulatory references
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EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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