Mercedes-Benz to investigate its diesel emissions tests

Daimler is investigating its biggest brand Mercedes-Benz on behalf of the US Department of Justice (DOJ) to determine if its diesel emissions testing procedures meet legal requirements.

The investigation follows a request for information by the DOJ last Friday. The car maker has launched a probe with the help of external lawyers to produce an official report.

Mercedes was issued with a class-action lawsuit in February, with accusations that its emissions tests didn’t meet requirements. The car maker responded by saying the claims were unfounded, but this week’s development pushes those accusations back into the limelight.

Mercedes is the latest in a growing number of manufacturers to come under pressure from regulators over their emissions testing procedures. Earlier this week, Japanese authorities raided Mitsubishi's offices to collect evidence after the car maker admitted rigging fuel economy tests.

Conversely, Volkswagen finally came to an agreement with US authorities after lengthy negotiations over its emissions scandal case. The car maker was found to be cheating emissions tests early last year, and has now announced it will offer compensation to affected US customers, while recalling offending vehicles across the world for a free fix.

A British investigation found that VW was the only car maker in the UK market to use emissions test defeat devices. However, the car maker’s latest diesel products have also been found to pollute the least amount of Nitrogen Oxides (NOx) in a new air quality study.