BMW i8 I12 / I15: the three-cylinder hybrid sports car, the exhaust guide

The 1.5 turbo three-cylinder: the combustion heart of the BMW i8 I12 / I15

In the i8, BMW placed a 1.5-litre turbocharged three-cylinder gasoline engine behind the occupants, in a rear mid-mounted position. On its own, it produces 231 hp and 320 Nm and drives the rear wheels, while an electric motor powers the front axle. The result is a lively, effective four-wheel-drive sports car, whose combustion engine remains its most expressive part.

A three-cylinder has a naturally distinctive sound, more gravelly and more rhythmic than a four-cylinder. On the i8, the factory exhaust holds back almost all of it, and the combustion engine goes unnoticed. The Rog valved exhaust takes its place without changing anything on the engine or its electronics, and lets you make this three-cylinder heard whenever you feel like it, without giving up silence the rest of the time.

What makes up the exhaust on your BMW i8 I12 / I15

An exhaust system is best understood in two parts. Here is what each one does, and what Rog replaces.

Your BMW i8 I12 / I15 in figures

What an exhaust changes straight away is the sound, the engine's breathing and the weight at the rear. For more power, add an ECU remap.

Manufacturer factory figures. Factory figures vary by version.

With or without an ECU remap, the exhaust fits and works. But it is an ECU remap at an approved tuning centre that truly unlocks your BMW i8 I12 / I15, and that is what we recommend.

The i8's turbocharged three-cylinder does not use all of its reserve as standard, and a Stage 2 can tap into it by working on the boost. On a hybrid powertrain, this work calls for a tuner who has mastered the whole system, and the result always depends on the vehicle's condition. The Rog exhaust fits naturally into this kind of approach.

Configuring your exhaust, step by step

3 choices, in the same order as the product page configurator.

1. 1

   Step 1 of 3: Material: stainless steel or titanium

   Titanium costs more than stainless steel; the price of each version is shown on the product page, in your currency.

   304 stainless steel

   Weight

   Baseline

   Sound

   Full and rounded

   Durable, corrosion-resistant, with a rounded, full sound: the most popular option.

   Titanium

   Weight

   Around 40% lighter

   Sound

   Metallic, crystal-clear

   For the same design, it weighs around 40% less than stainless steel. A more metallic note at high revs and a look all of its own, from brushed to blued.

   Both materials age well: 304 stainless steel copes with winter and salt, and titanium does not rust. Stainless steel or titanium: what really changes.

2. 2

   Step 2 of 3: Front section: downpipe and catalytic converter

   Optional: the downpipe on your BMW i8 I12 / I15, with its catalytic converter. Sound rating out of 10, valves open: the factory exhaust sits at 3.

   Cat-back only

   Included

   7/10

   Factory emissions control

   Nothing changes at the front: the cat-back alone is already enough to change the car.

   200-cell sports catalytic converter

   8/10

   Road use and inspection

   The everyday compromise: emissions control is still there, and breathing improves noticeably.

   100-cell sports catalytic converter

   9/10

   Inspection: depends on local rules

   One step further: more flow, a more aggressive sound, reduced emissions control.

   Decat

   10/10

   Track use

   Everything unleashed: maximum flow and unrestrained sound, for the track.

   Sound intensity, on a scale of 0 to 10

   1. 10/10Decat downpipe + Rog cat-back
   2. 9/10100-cell sports catalytic converter + Rog cat-back
   3. 8/10200-cell sports catalytic converter + Rog cat-back
   4. 7/10Rog cat-back only, factory catalytic converter retained
   5. 3/10Factory exhaust, for comparison

   Valves open. With the valves closed, every configuration becomes discreet again.

   What about the engine warning light? With a sports cat, it can come on with some engines: the sensor placed after the catalytic converter measures a different level of emissions control from the original. It is not a mechanical failure, but a warning light should never be masked or cleared without dealing with its cause: the right answer is a catalytic converter suited to the engine, with a map by a tuner who takes it into account. The decat version, for track use only, almost always triggers it. If this happens to you, write to us and we will point you in the right direction. Passing vehicle inspection with a sports exhaust.

3. 3

   Step 3 of 3: Valves: Rog remote or factory control

   Two ways to control the valves on your BMW i8 I12 / I15.

   Rog remote

   

   The simplest solution: a control unit in the trunk and a remote, open or closed at the press of a button, whatever mode you are in. A question while fitting? We will get back to you.

   Factory control

   • Only for vehicles fitted with factory valves
   • Controlled by the drive modes

   Does your vehicle have factory valves? The exhaust keeps their existing control: the drive modes operate the valves, as before, with no added electronics.

   On a long journey, what matters is the absence of drone at a steady speed. With the valves closed, the exhaust keeps the cabin calm; the show is still there whenever you ask for it. More about exhaust drone.

The Rog sound signature on the i8's three-cylinder

The i8's three-cylinder has a gravelly, rhythmic, almost rough voice that contrasts with the car's futuristic image. As standard, you only hear a distant echo of it: the factory exhaust is designed to keep the combustion engine in the background, even when it is working at full load.

In discreet mode, with the valves closed, the i8 keeps its restraint, ideal for crossing town or setting off early in the morning. With the valves open, the three-cylinder comes out of its shell: its distinctive grain can be heard with every acceleration, and the car gains a sound presence to match its looks.

From order to fitting

1. Configuration

   You choose the options for your BMW i8 I12 / I15 and enter its VIN, found in box E of the registration document or at the base of the windshield.

2. Check

   We confirm compatibility with your car before we build it.

3. Manufacturing

   Made to order, for your BMW i8 I12 / I15.

4. Delivery

   Free, insured delivery, with tracking sent on dispatch.

5. Fitting

   Clamps and gaskets, no welding: two hours on average at the garage of your choice.

20 working days from order confirmation to delivery

Warranty

3 years, parts and workmanship, from the date of purchase

Payment

Card, PayPal or bank transfer

Installation

At the garage of your choice

What about the manufacturer's warranty? In Europe, fitting a part from another brand is not enough on its own to void it; the manufacturer has to prove the link between that part and the fault. Our article on the manufacturer's warranty.

Our recommendations for your BMW i8 I12 / I15

• Daily driving

  • Stainless
  • Cat-back only
  • Rog remote

  Your BMW i8 I12 / I15 stays easy to live with, the factory emissions control is retained, and you open the valves whenever you decide.

  View this configuration

• Fast road

  • Titanium
  • 200-cell downpipe
  • ECU remap

  For great roads: more voice and more response, while staying road-friendly.

  View this configuration

• Track

  • Titanium
  • Decat downpipe
  • Stage 2

  The most extreme configuration, for track use only.

  View this configuration

These profiles are starting points. The right choice is often made in a few messages.

BMW i8 I12 / I15: your questions

Further reading

• All BMW exhaust systems
• Stage 2: the role of the downpipe
• How to pass vehicle inspection with a modified exhaust
• Pop & Bang: how it works, and is it risky?
• Stainless steel or titanium: what really changes
• The 28 brands we cover