Real World Emissions Testing May Lead To Larger Engines

Blame it on Volkswagen. Until the diesel emissions cheating scandal broke more than a year ago, the world of automobiles was cruising along, serene in the knowledge that emissions testing protocols were doing a pretty good job of protecting us from cars that pollute the environment. Then the world shifted on its axis and we found, much to everyone’s dismay, that emissions testing in the lab is worthless when it comes to measuring real world performance.

real world emissions testing

In order to meet increasingly rigorous emissions regulations, automakers for years have been downsizing the engines they use. V-8’s became V-6’s. 4 cylinders became 3 cylinders. Fiat and some other manufacturers started offering 2 cylinder engines in some models. The trick was to add turbochargers to the smaller engines to make up for the decrease in displacement.

In theory, the smaller engines would perform brilliantly in emissions testing performed in laboratories using dynomometers computer simulations. That part turned out to be true. But when Dieselgate came along, it made people realize that those emissions testing protocols were worthless when it comes to measuring performance in real world driving situation.

The discrepancy was particularly noticeable with diesel engines. The smaller the engines got, the higher their real world emissions. Apparently the extra heat created by adding turbochargers causes NOx emissions to soar to levels as much as 15 times higher than measured in the lab. The smaller gas engines have issues, too. They become less fuel efficient in real world driving. Worse, they tend to spew particulates out the tailpipe along with increased amounts of carbon monoxide.

“They might be doing OK in the current European test cycle, but in the real world they are not performing,” said Pavan Potluri, an analyst with influential forecaster IHS Automotive. “So there’s actually a bit of ‘upsizing’ going on, particularly in diesel.”

The European Union is about to make real world emissions testing mandatory and that is causing a kerfluffle in the industry. “The techniques we’ve used to reduce engine capacities will no longer allow us to meet emissions standards,” said Alain Raposo, head of powertrain at Renault-Nissan. “We’re reaching the limits of downsizing,” he said at the Paris auto show this month.

The tougher real world tests may kill diesel engines smaller than 1.5 liters and gas engines below about 1.2, analysts predict. That in turn increases the challenge of meeting CO2 goals, adding urgency to the scramble for electric cars and hybrids. The issue is less serious in North America and China, where the push to downsize engines has not reached the levels seen in Europe. But it does show that going smaller and bolting on a turbo is not the magic solution some thought it was.

What may work, however, is marrying smaller engines to electric motors to create a powertrain that meets the needs of motorists and the environment. In a curious way, the troubles at Volkswagen may actually end up making electric cars — or partially electric cars — more common in the marketplace.

Source: Reuters  Photo via Hybrid Cars

Steve Hanley

Closely following the transition from internal combustion to electricity. Whether it's cars, trucks, ships, or airplanes, sustainability is the key. Please follow me on Google + and Twitter.