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We’re moving away from heat engines with the transition from ICE cars to EVs, but heat still plays a big part in the performance and wellbeing of all electric cars.

With that in mind, Continental has developed a device called an e-Motor Rotor Temperature Sensor (eRTS), which monitors temperature more accurately than software-based simulation and should reduce the amount of rare-earth material used in permanent magnet synchronous motors.

Batteries, motors and inverters all generate heat due to the power they are handling and the majority of them use liquid cooling.

Most EVs also use permanent magnet motors that have rare-earth magnets embedded in the rotors. Although some manufacturers have chosen to substitute permanent magnets for electromagnetic windings in the rotor, rare-earth permanent magnets have traditionally been the go-to solution to achieve high power and efficiency.

However, the environmental impact of extracting and processing them is significant. The current geopolitical turmoil is also raising concerns over supply and most of them come from China, so alternatives – like asynchronous magnet-free motors – or using less of them are advantageous.

Permanent magnets also have a vulnerability: overheating. If magnetised material reaches a certain temperature known as the Curie point, which varies depending on the material, it can become demagnetised. If that happens to the magnets in an EV motor, then the performance will at least diminish and at worst the motor will fail.

The heat of rotors today is not measured directly but calculated by algorithms developed through simulation and based on temperatures recorded by a sensor on the stator (the windings surrounding the rotor that don’t move).

Because the temperature is calculated rather than directly measured, manufacturers leave a fairly large margin of error on the figure calculated by the algorithms of 15deg C. The temperature of an EV rotor can rise to around 150deg C, so to protect magnets from demagnetisation, enough rare-earth elements must be used to cover the entire tolerance range and ensure the magnets don’t overheat. 

Using a temperature sensor is much more precise. It reduces that margin to only 3deg C and enables the use of less rare-earth material.

The eRTS is a clever device in other ways, too, and can generate its own power. It’s in two parts. One is a mote sensor (mote means small particle) embedded in the rotor, which senses the temperature of the magnets.

The second is a transducer (which converts one kind of energy into another) sitting outside the motor casing. Through piezo ultrasound, the mote can generate the tiny amount of power it needs wirelessly, as well as transmitting the temperature data.

Sometimes the smallest things can have great significance.

Volkswagen is readying its most powerful Golf yet, with plans to fit a 25th anniversary version of the R with the same turbocharged 2.5-litre five-cylinder petrol engine used by the Audi RS3.

The model is expected to arrive in 2027 to serve as a send-off for the pure-petrol Golf before its transition to electrification. It also confirms Audi’s commitment to keeping the 'EA855' five-pot engine alive following suggestions that new emission regulations would kill it off.

With that unit fitted, the special Golf is set to mark a significant step up from the current Golf R 333. While that car uses VW’s ubiquitous 'EA888' 2.0-litre turbo petrol four, uprated to 328bhp and 295lb ft, the run-out’s 2.5-litre turbo five delivers 394bhp and 354lb ft in the current RS3.

That engine is likely to make the new R the quickest Golf to 62mph too. The RS3 can dispatch the sprint in 3.8sec whereas the R 333 completes the run in 4.6sec.

The power output could be pushed further still. Sebastian Grams, former managing director of Audi Sport, told Autocar in 2023 that “there's still a way to go” with the five-cylinder engine compared with the RS3 Performance Edition, its most potent variant to date. That car, which was launched in 2023 and limited to 300 models globally, put out 401bhp and 369lb ft.

The five-cylinder engine has become a signature feature of the RS3, so its fitment into a Golf is being hailed by Volkswagen as a significant moment. The unit is also used in other Volkswagen Group models, including the Cupra Formentor VZ5.

To keep the engine alive beyond the Euro 7 November 2026 deadline, Audi will update the unit’s hardware. Likely changes include a new particulate filter, more sensitive NOx sensors, recalibrated injection mapping and higher cell-density catalysts.

To accommodate the new engine, suspension tweaks will be needed to support the added mass.

The four-cylinder Golf R 333 already benefits from 1.5deg of negative front camber, stiffer rear subframe mounts, bespoke software calibration for the adaptive dampers and reprofiled bushings. However, the required changes may include a move to 2.0deg of negative front camber, upgraded top mounts, reinforced knuckles and additional chassis bracing to increase torsional rigidity.

The RS3 also uses a stiffer front axle layout with bespoke pivot bearings to sharpen initial turn-in. Similar hardware could find its way into the Golf R if packaging allows.

The addition of the five-cylinder engine is expected to bring a modest weight increase over the current Golf R’s 1545kg. Given that the near-technically identical RS3 tips the scales at around 1570kg, the five-cylinder Golf R is likely gain around 25kg.

To keep weight down, forged aluminium Warmenau wheels are expected to feature. They’re likely to be shod with the semi-slick Bridgestone Potenza Race tyres already used on the Golf GTI Edition 50. Wider tracks and recalibrated software are also anticipated to increase grip and control.

Bigger brakes will be needed to cope with the extra power. For reference, the Golf R 333 has 357mm steel discs, with the RS3 using 380mm carbon-ceramics.

Autocar understands the Golf R will adopt a reconfigured version of Volkswagen’s seven-speed dual-clutch gearbox, including revised gear ratios and launch control.

It’s also expected to use the RS3’s Torque Splitter – a mechanical torque-vectoring rear differential – which helped the RS3 set a Nürburgring lap time of 7min 40.748sec in 2021. VW is aiming for the special model to propel the Golf R back to the top of Volkswagen’s in-house leaderboard. The Golf GTI Edition 50 is currently the quickest variant around the Nordschleife with a time of 7min 46.13sec. For reference, the Golf R 25 Years achieved 7min 47.31sec.

Styling changes are expected too. Spy photos of the car testing show that new intakes have been cut into the bonnet, and larger ones adorn the front end, to significantly improve airflow to the new engine.

At the rear, a more aggressive roof-mounted spoiler can be seen, as well as a new diffuser. The production model’s quad exhausts are expected to feature titanium tips and active flaps to further refine acoustics.

Inside, weight-saving measures such as lightweight bucket options are likely to feature, similar to the GTI Edition 50.

An unveiling is tipped to take place next year, with UK sales set to coincide with Volkswagen R’s 25th anniversary in 2027.

When it arrives, the five-pot Golf is expected to be the last to use a non-electrified powertrain. VW plans to launch its first full-hybrid Golf around the same time, using the same hybrid set-up mooted for the next-generation T-Roc. Further-developed versions of its plug-in hybrid system – such as in the GTE – will follow ahead of the launch of the first fully electric Golf, which is pencilled in to arrive by the end of the decade.