Ford is investigating the testing procedure it uses for its vehicle emissions standards and fuel economy after employees raised concerns about potential inaccuracies.

The vehicle manufacturer has hired an outside company to conduct the investigation into the potential issues, which it says do not involve the use of defeat devices,

It is also evaluating potential changes to the road-load modelling process – the force on a vehicle while driving at a constant speed over a smooth – including engineering, technical and governance components.

The first vehicle it is investigating is the 2019 Ranger but it will eventually test others.

Kim Pittel, Group Vice President for Sustainability, Environment & Safety Engineering, Ford Motor Company said: “In September, a handful of employees raised a concern through our Speak Up employee reporting channel regarding the analytical modelling that is part of our US fuel economy and emissions compliance process.

“At Ford, we believe that trust in our brand is earned by acting with integrity and transparency. As part of this, we have a process for looking at how we perform and behave in our broad and complex company. As a result of the concern, we have taken a number of actions.”

The company added it has voluntarily shared the potential concerns with the US Environmental Protection Agency and the California Air Resources Board.