BMW i8 Roadster: giving BMW's most spectacular silhouette the voice it deserves with an Active Sound Thor Level 4
Park a BMW i8 Roadster anywhere and watch what happens. The butterfly doors opening towards the sky, the futuristic supercar silhouette. Within seconds, every head turns and the car becomes the centre of attention.
Then the engine starts. And that is where the deal breaks down. This spectacular machine, looking like a prototype that has escaped from a motor show, springs to life with a surprisingly civilised purr. A three-cylinder petrol engine paired with an electric motor. Technically impressive. Emotionally frustrating.
The owner of this i8 Roadster wanted to fix that last imbalance. Here is how a Thor Level 4 Kit finally gave the car a sound to match what it is.
The supercar that never got the voice it was promised
Launched in 2014 and later joined by the Roadster version in 2018, the BMW i8 belongs to that rare breed of cars that defined an era through sheer audacity. A series-production hybrid architecture, a carbon-fibre chassis, a concept-car silhouette and butterfly doors. For years, the i8 embodied the future as BMW imagined it: sporty, technological, clean.
Under the bonnet, however, the mechanics have always felt at odds with everything else. A 1.5-litre three-cylinder turbo petrol engine paired with an electric motor, for a combined output of around 374 horsepower. It is efficient, it is innovative, it is on-trend. But it does not sound like a supercar. It sounds like a high-end urban runabout.
BMW tried to compensate with a factory engine sound system, piped into the cabin. The result is acceptable, but falls well short of what the car's silhouette promises from the outside. The i8 has always suffered from this contradiction: a Ferrari look with the voice of a petrol city car.
Why a Level 4 on this i8 Roadster
For this installation, the choice fell on a Thor Level 4 Kit, made up of two Thunder speakers in metal.
Technically, the i8 is one of the best-insulated cars in the BMW range. The three-cylinder petrol engine is deliberately muted, and the electric motor naturally brings a silent dimension to many driving scenarios. For a sound upgrade to be both noticeable and lasting on this type of architecture, the configuration needs to produce real acoustic pressure. The Level 4, with its two Thunder units, does exactly that.
Symbolically, the i8 deserves nothing less than the most expressive setup. This is a special-occasion car, one you take out for the joy of it, to show off, to share. A more modest configuration would fall short of the car's sensory potential. On an i8, the goal is not discretion: it is coherence between the car and the aura it projects.
A 100 % reversible installation on a car that has become a collector's piece
With production ending in 2020 and a relatively limited number of examples on the road, the BMW i8 has entered a new chapter of its existence: that of a collector's car. The owner of this i8 Roadster is fully aware of it. His car is not a disposable i8. It is meant to be kept, maintained and passed on.
The installation was therefore approached with absolute respect for the vehicle. No welding on original BMW parts, no structural drilling, no cuts to the wiring harness. The two Thunder speakers were fitted under the car in invisible, protected areas. The control module is housed in the boot, without encroaching on the already limited storage space of an i8 Roadster.
At any time, the system can be removed by an approved installer without leaving the slightest trace. The car then returns to its strictly original condition — which is essential to preserve its long-term collector value.
The final result on this BMW i8 Roadster
With a Thor Level 4 Kit, this i8 Roadster has finally caught up, on the acoustic side, with the image it projects visually. The engine starts, until now so understated, now have real presence. Accelerations are accompanied by a convincing sound signature. Drive-bys past cafés, terraces or groups of onlookers become a complete event — not just a visual one.
The car's hybrid architecture is untouched. The engine, the transmission, the electric system — everything works exactly as it did when it left the factory. The fully electric mode remains available and works normally. The Thor system simply layers on top, fully adjustable through the mobile app: volume control, one-touch deactivation.
For owners of an i8 Coupé, an i8 Roadster, or any hybrid sports car whose visual potential far outweighs its factory sound signature, this is the upgrade that finally reconciles the car with what it has always wanted to be.
Does your supercar deserve a voice as bold as its design?
The Thor system is available in several configurations to suit every vehicle, from Level 1 to Level 4 + Echo. For hybrid sports cars and exceptional vehicles, the Level 4 remains the most expressive configuration — while staying fully adjustable and 100 % reversible.
Explore Thor kits
The videos of this installation
Frequently asked questions about this type of installation
Yes. The Thor system is compatible with both the BMW i8 Coupé (launched in 2014) and the i8 Roadster (launched in 2018). The installation is adapted to the vehicle's specific hybrid architecture.
Yes. This is precisely one of the great advantages of the Thor system on an i8. Even when the 3-cylinder combustion engine is switched off and the car is running in pure electric mode, the Thor system remains active and can produce a sporty sound signature. This radically transforms the EV mode experience, which is otherwise completely silent by default.
No. The Thor system is entirely independent of the engine, transmission, and exhaust line. No original part is modified, and the installation remains fully reversible. The warranty is not affected, and the vehicle's collector value is preserved since the system can be removed at any time without leaving a trace.
Installing a Thor Level 4 Kit on an i8 generally takes a few hours at an approved installer, with particular care taken to respect the vehicle. The car is ready the same day, with the system calibrated and the app configured.
