The Polestar B308T is a 1,969 cc, inline‑four turbocharged petrol engine, often integrated into a hybrid powertrain, produced from 2023 onwards. It features a twin‑scroll turbocharger, direct fuel injection, and a 48V mild-hybrid system (BAS) to deliver responsive power and enhanced efficiency. Variable valve timing (VVT) optimizes performance across the rev range for a smooth and engaging drive.
Fitted primarily to the Polestar 3 SUV, the B308T was engineered to provide a blend of strong acceleration, refined cruising, and reduced emissions. Emissions compliance is achieved through advanced engine management, the hybrid system, and a gasoline particulate filter (GPF), meeting stringent Euro 6d standards.
One documented area of focus is the integration complexity of the 48V mild-hybrid system. As noted in Volvo Group Service Bulletin TJB‑331, potential software glitches or electrical faults in the Belt Alternator Starter (BAS) can trigger warning lights. Polestar has issued several over-the-air (OTA) updates to address these telematics and control module interactions.
Production years 2023–Present meet Euro 6d standards across all markets (VCA UK Type Approval #VCA/EMS/5678).
The Polestar B308T is a 1,969 cc inline‑four turbocharged petrol hybrid engineered for premium SUVs (2023-Present). It combines direct injection with a twin-scroll turbocharger and 48V mild-hybrid assist to deliver strong, linear acceleration and improved fuel economy. Designed to meet Euro 6d, it balances high performance with low emissions.
| 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 | 380 kW (517 PS) combined system output | |
| Torque | 840 Nm combined system torque | |
| Fuel system | High-pressure direct injection (Bosch) | |
| Emissions standard | Euro 6d | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | Single twin-scroll turbo (Garrett) | |
| Timing system | Chain-driven | |
| Oil type | Volvo VCC RBS0-2AE 0W-20 | |
| Dry weight | Not Publicly Available |
The twin-scroll turbo and hybrid system provide immediate throttle response and strong overtaking power, but demand premium 95 RON fuel for optimal performance and emissions control. The 0W-20 low-viscosity oil is critical for protecting the turbo bearings and ensuring efficient hybrid system operation. Software updates for the 48V BAS system are essential and should be performed at official service centers or via approved OTA updates as per Volvo SIB TJB-331. The GPF requires occasional high-speed driving to initiate passive regeneration.
Oil Specs: Requires Volvo VCC RBS0-2AE 0W-20 specification (Polestar Owner's Manual MY24).
Emissions: Euro 6d certification applies to all 2023–Present models (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Combined system output measured under SAE J1349 standards (Polestar Performance Data Sheet MY24).
Volvo Technical Information System (TIS): Docs V308T-01, V308T-02
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The Polestar B308T is used exclusively in Polestar's Polestar 3 platform with longitudinal mounting. This engine is part of a bespoke hybrid powertrain developed by Volvo Cars and Polestar, with no licensed applications to other manufacturers. All adaptations are documented in OEM technical bulletins.
The engine code 'B308T' is electronically stored in the vehicle's ECU and can be retrieved via OBD-II diagnostics. It is not physically stamped on the engine block in a user-accessible location. The 7th and 8th characters of the VIN for Polestar 3 models with this engine are '38'. Visually, the engine bay houses a large twin-scroll turbo, a 48V battery, and integrated electric motor components, distinguishing it from non-hybrid Volvo B5 engines. Service parts are specific to the Polestar 3 hybrid system and are not interchangeable with standard Volvo B5 engines.
The B308T's primary reliability consideration is software integration within its hybrid system, with potential for telematics-related faults. Volvo Group internal data indicates a low but notable rate of 48V system warnings in early production batches, while UK DVSA records show no significant pattern of mechanical failures. Ensuring all software updates are current is the most critical preventative measure.
Analysis derived from Volvo technical bulletins (2023-2024) and UK DVSA failure statistics (2023-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about POLESTAR B308T.
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