The increasing number of electric vehicles on our roads not only has a positive impact on the climate and air quality, but also on traffic noise. The extent to which the noise levels of electric vehicles and combustion engines differ has not yet been systematically investigated. Empa and the Touring Club Switzerland have worked closely together on an extensive research project to find out how the noise level of comparable cars with different drive systems differs depending on the driving style.
Nine car pairs in direct comparison
At the TCS Stockental Driving Centre, Empa and TCS compared nine pairs of cars from different categories — from the Peugeot (e)-208 to the VW ID.Buzz and its combustion counterpart, the VW Multivan. The experts took various measurements on the approximately 100 metre long test track and examined the noise level at constant speed and during acceleration. For this purpose, Empa researchers developed new sensor modules that were mounted on the test vehicles and enabled the test drivers to complete various driving profiles precisely and repeatably.
Large differences in acceleration
This showed that electric cars are significantly quieter than their combustion engine counterparts, particularly when accelerating. Especially in acceleration situations below 40 kilometres per hour, such as when starting at traffic lights, the noise level of electric cars is significantly lower on average. Depending on the vehicle pair, the difference is more than three decibels, which corresponds to a halving of the sound intensity. The difference between the drive types increases significantly with increasing acceleration: the higher the acceleration and the lower the speed, the louder the combustion engine is compared to the electric car.
However, the results were different when driving past at constant speeds of between 30 and 60 kilometres per hour. On average, there were no significant noise differences between electric cars and combustion engines, as tyre noise dominates and drowns out the engine noise.
Successful collaboration between Empa and TCS
For Sascha Grunder, Head of Test & Technology at TCS, the study brought important findings to light: “With this detailed study, we have broken new ground and can show that electric cars are quieter than combustion engines, especially at low speeds and high acceleration. For TCS, it was a privilege to work with Empa’s scientists and to provide the noise experts with real data for the first time.”
Reto Pieren, Group Leader Environmental Acoustics at Empa, also rates the study positively: “The results are an important contribution to noise research and show that e‑mobility contributes to noise reduction in urban environments. The collaboration with TCS was enriching and I look forward to continuing it.”
The results of the study will be presented at the international scientific conference ‘Forum Acusticum’ in Malaga. The study also forms the basis for further research projects. The researchers will continue to evaluate and analyse the measurement data until the end of 2025. In the next step, Empa and TCS want to jointly investigate the influence of tyre type and road surface properties on noise levels. These investigations will take place in spring 2026 and the results are expected to be published at the end of next year.
The TCS was founded in Geneva in 1896 as a non-profit association and comprises 23 sections and a central office. As an important point of contact for the cantonal and federal authorities in matters of mobility, the TCS organization is committed to freedom of choice in the means of transport. For more than a century, we have been committed to the safety of all road users through awareness campaigns and studies on the quality of transport infrastructure. With around 1.6 million members, TCS is the largest mobility club in Switzerland. For more information, please visit: www.tcs.ch.
