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 pr…
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 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 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.
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As a new engine (2023–present), long-term data is limited. Early indications suggest strong mechanical reliability. The primary focus is on software updates for the 48V hybrid system. Regular servicing with the correct 0W-20 oil and using 95 RON fuel are key to ensuring longevity.
The most frequently reported issues involve the 48V mild-hybrid system triggering warning lights, often resolved by software updates. Other potential concerns include GPF clogging from short trips and minor coolant leaks from the thermostat housing in early builds.
The B308T engine is currently used exclusively in the Polestar 3 SUV, specifically in the 'Dual Motor Performance Pack' variant. It is not available in any other Polestar or Volvo model as of 2025.
Official tuning is not offered by Polestar. While aftermarket ECU remaps may be possible, they are complex due to the integrated hybrid system and could void the warranty. Significant power gains would likely require hardware upgrades beyond the ECU.
Official WLTP combined fuel economy for the Polestar 3 with the B308T is approximately 1.4 L/100km (201 mpg UK) due to its electric range. Real-world consumption for the petrol engine, once the battery is depleted, is around 8.5-10.5 L/100km (27-22 mpg UK) depending on driving style.
Yes. Like virtually all modern DOHC engines, the B308T is an interference design. A failure of the timing chain could result in catastrophic damage as the pistons would collide with the open valves. The chain is designed for the engine's lifetime under normal conditions.
Polestar mandates the use of Volvo VCC RBS0-2AE specification 0W-20 synthetic oil. This low-viscosity oil is crucial for the engine's efficiency, turbocharger protection, and the operation of the 48V hybrid system. Using the wrong oil can cause damage.
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