The trucking industry in the U.S. is bracing for federal regulators to soon propose new rules requiring the fuel efficiency of new trucks to increase by as much as 40% by 2027 from 2010’s level.

That’s according to a story this week from Reuters, in which it reports that some trucking aren’t necessarily opposed to tougher standards. The reason is because fuel is one of any trucking operation’s greatest costs, but the real fight may lie in the smaller details of the plan.

For instance, the U.S. Environmental Protection Agency earlier said it will introduce “performance-based” standards, meaning truck makers can use a variety of options to hit fuel economy and emissions targets, ranging from changes in the engine all the way to putting additions on trucks and trailer bodies.

However, OEMs are split on how they want the government to measure emissions. Some, such as Cummins and Eaton, reportedly want the truck engines measured alone, while Daimler and Volvo want emissions measured for the truck entirely.

Canada has indicated it will likely follow the U.S. proposal, part of a wider Obama administration initiative to curb greenhouse gas emissions.

Read more about this from Reuters.