Emissions testers find diesel cars in Europe pollute more in cool weather

(Tech Xplore)—The BBC is reporting that a company called Emissions Analytics has found that many car makers have programmed their cars to turn off (or down) emissions control systems at approximately 18 degrees Celsius, which some might consider as "cool" rather than the "cold" being reported by automobile makers. Representatives for EA suggested that many car makers appear to be taking advantage of a rule that allows for turning off, or reducing emissions controls during cold weather to prevent unreasonable wear and tear on motors parts, in order to give drivers more miles per gallon of gas.

Most cars in Europe are subject to the Euro 5 rules imposed on cars made between the years 2009 and 2011—the rules were meant to curb air pollution, most particularly those that have been labeled as greenhouse gas emissions—with diesel cars, that pollutant is nitrogen oxide (N2O). EA found that of 213 cars tested from 31 different manufacturers, that the average vehicle emitted 3.6 times as much N2O as is supposed to be allowed by Euro 5 rules—in temperatures above 18C°. When testing below that threshold, they found that the average car was emitting 4.6 times the allowable limit.

They noted that the problem has crept into newer vehicles as well, with those that are supposed to conform to the more strict Euro 6 rules. For those cars tested, the average vehicle emitted 2.9 times the allowable limit in temperatures above 18C°, but the average vehicle emitted 4.2 times the allowed limit below that temperature.

These findings by EA suggest, of course, that millions of vehicles in Europe are emitting much more pollution than has been believed, all in the name of increased gas mileage—and because cars last a long time, it appears many will continue to do so for ten or fifteen years into the future.

Prior testing by other agencies in other countries has led some car makers to offer software upgrades to some vehicles, modifying the temperature at which the vehicle will turn down or off emission control systems—though it is doubtful many consumers will take advantage of such an offer as it will mean an immediate and permanent reduction in gas mileage.