Study Claims Diesels Generate More CO2 Than Gasoline Engines

Diesels may emit less carbon dioxide than comparable gasoline engines, but their lifecycle CO₂ contribution is greater, according to Transport & Environment.

Brussels-based T&E, which campaigns for sustainable transportation options, agrees that tailpipe emissions of CO₂ may be lower for diesels. But it analysis says the difference has narrowed significantly in recent years as gasoline engines have become more fuel efficient. Fuel economy and CO₂ emissions from engines that burn fossil fuel are directly related.

European carmakers describe diesels as emitting about 20% less CO₂ than comparable gasoline engines, making them a critical element in efforts to meet current and future EU limits for CO₂ emissions.

T&E notes that gasoline and diesel iterations of the current-model Volkswagen Golf have identical CO₂ emission ratings (114 g/km), but the diesel version is 74 kg (163 lb) heavier and costs nearly €2,800 ($3,300) more.

T&E also asserts that any remaining CO₂ advantage for diesels is more than offset by the impact of refining diesel fuel and manufacturing the sturdier components required for diesel engines.

The report further points out that European tax laws have made diesel fuel cheaper than gasoline, thereby encouraging diesel owners to put more miles on their vehicles. The additional usage works to offset any fuel savings compared with gasoline-fueled vehicles.