Why Subaru Discontinued Diesel Engines (And Never Offered Them In The US)

IN 2008, automaker Subaru unveiled its EE20, a 2.0L flat-four common-rail turbodiesel engine, as an option in European versions of popular models like the Outback and Legacy. The engine offered 148 horsepower and 258 pound-feet of torque, which kicked in at 1,800 rpm. Even more impressive was the estimated fuel economy of 49 highway miles per gallon. The automaker planned to release this option in the U.S. around 2010, but by 2016, not only had Americans failed to get their hands on Subaru's EE20 diesel, but further development on it had ceased.

"With diesel it is too difficult to keep the exhaust gas clean," Masahiko Inoue, project manager over the Impreza, told WhichCar.com.au in 2016. "But in future I think we will not have diesel." Inoue added that the manufacturer was instead going to focus on gas engine turbocharging and hybrid technology.

The main reason Subaru never launched its diesel boxer engine stateside was stringent U.S. emission standards that the manufacturer strained to reach. But even if the automaker had brought its EE20 to America, it likely would've faced some challenges, as it was plagued by a serious flaw that garnered it negative perceptions in Europe. 

The 1970s were an interesting time in the American automobile industry, offering a wild swing from some of the most potent big-block muscle cars to cratering performance levels due to new emissions restrictions. As manufacturer's scrambled to generate decent output while enhancing efficiency, it gave rise to one of the worst engines major companies ever put in a production vehicle.

With diesel engines known for being more fuel-efficient than their gasoline counterparts, Oldsmobile decided to develop a diesel in the late '70s to combat rising oil prices. However, the diesel-powered Oldsmobile Cutlass was ultimately a flop for many reasons, including a hurried development cycle. The fallout from this failed experiment left a lasting bad taste in Americans' mouths.

Another reason diesel cars in the U.S. didn't see the same popularity as they did in Europe had to do with taxes. While Americans in the '90s saw relatively cheap gasoline prices, countries across the Atlantic like Spain and Belgium began heavily taxing gasoline and providing incentives for diesel. This led to diesel being far more popular in Europe than in the U.S.

Diesel technology has dramatically improved over the years, and many Americans count on a turbodiesel power plant for potent torque in their trucks. However, there are still some downsides to diesel that may discourage some drivers. The biggest knock against them is cost.

For example, some truck brands in the recent past have piled on almost $10,000 extra for a diesel power train over the gasoline variant, and this added cost isn't just related to trucks. Back in 2008, Motor Trend reviewed the Subaru boxer diesel (European version) and predicted the U.S. price tag for the diesel model might add $2,000 — almost $3,000 today — or more to the cost.

In addition, the average U.S. price per gallon for gasoline in 2025 is $3.06, whereas diesel sits at $3.55, the U.S. Energy Information Administration says. While diesel's enhanced fuel economy certainly can help reduce fill-up frequency, these benefits are most notable on long-distance drives. These are just a few of the things you should know before buying a diesel-powered car or truck.