While many companies are continuing to downsize, new research suggests that lower displacement engines may produce even higher levels of CO2 and NOx.

It seems for decades automakers have been downsizing their engines in hopes of reducing emissions — but new reports are putting that thinking into questioning. According to Reuters, companies like Renault, Volkswagen, and others are beginning to scale up engine sizes to reduce environmental impact.

The call for larger engine displacements comes fresh off of Volkswagen’s Dieselgate scandal, which put unrealistic testing procedures in the spotlight. These tests, conducted at impractically moderate temperatures and speeds, failed to show that smaller displacement engines, both gasoline and diesel, actually exceeded legal emission levels when in real-world settings more so than some larger displacement options. Some of its biggest offenders being Fiat, Renault, and Opel's newest "Euro 6" diesel engine.

Already though, companies like Renault-Nissan are taking the tests into account with a plan to upsize some of their smallest engine offerings. “The techniques we’ve used to reduce engine capacities will no longer allow us to meet emissions standards,” said head of powertrain at Nissan-Renault, Alain Raposo, in a recent interview at the Paris Motor Show. “We’re reaching the limits of downsizing.”

The results may call for the end of diesel engines with a displacement of under 1.5 liters, and gasoline engines under 1.2 liters. Already, Volkswagen has lined up a 1.6-liter replacement for its 1.4-liter three-cylinder diesel in cars like the Polo, while Renault is following suit with a 10 percent enlargement to its 1.6-liter R9M diesel engine, which was introduced new in 2011.

“It becomes apparent that a small engine is not an advantage,” said Thomas Weber, head of research and development at Mercedes. “That’s why we didn’t jump to the three-cylinder trend.” 

In the future, along with increasing displacement on some of its smallest engine offerings, these companies will likely turn to electric motors and hybrid powertrains as a solution, as many have done already.

Source: Reuters