The 4 Cyl turbo diesel is, I think same as the sprinter van base Diesel engine. That engine was discontinued on the Sprinter, same time, so MB would only have to get one diesel EPA certified...thank you Volkswagen!” It is not sold in Canada and there are many iterations of diesels in Europe. I just sold my GL350 bluetec, primarily due to the emissions requirements, which here in the US are more rigorous than anywhere else in the world.

The emmissions requirememts have taken a perfectly good engine, and greatly complicated the reliability, especially with the required exhaust gas recirculating valve, which essentially re-routes exhaust, which is carbon rich, back into the engine. I replaced my GL with the gas GLE 350. The difference in torque (lower) is noticeable.

I also purchased a sprinter van for my business, and was able to buy a special extended warranty on the emmissions...which is a separate service contract. It would make sense to carefully review the MB extended warranty - which I highly recommend- to identify if it includes the diesel emmissions and DEF (diesel exhaust fluid) system.

I seriously considered the GLE 300D and would have purchased one, if MB was still producing the, for the states. For now, absent the Sprinter van, they are out of the diesel market, I ultimately opted to go with the gas version. I’d be very interested to hear the outcome. I hope this helps.

I’m not clear on the origins of the 4 cyl diesel, but suspect it has been in use elsewhere, since MB builds a lot of diesels outside the states. I really enjoyed my GL 350, and without the extended warranty would have had significant expenses. If you research the v6 diesels on the site, you will discover there are some known problems.

My GL blew the oil cooler and engine seals, under warranty. It’s at least a $4,000 service bill. Unreleated to diesel, the air Matic front suspension and compressor failed, also under warranty (this problem for GL usually evidences itself between 75 - 150k, gas or diesel) and I suspect rear suspension would be soon too...had about 90k on the odo. Previously i I had a 2008 R class diesel, the engine was perfect! All the other stuff, however cost me about 13k in service over 2 years. So maintanence is a factor.

I tradeded my GL almost at the end of the warranty with the expectation that it would continue to cost real money to service. I couldn’t find much on the 4 cyl diesel, pro or con, but had hoped it would prove to be a better long term engine. Ultimately, it’s the U.S. diesel emmissions that complicates what should be a solid design. While it is my preference to drive diesels, until MB puts one into to passenger car service again, new, and supports it, I’ll pass.

Since there is no (negative) evidence on the 4 cyl, it could turn out well. That engine was also used for a couple of years on the GLK and the E class sedan from I think 2014 - 2016. Best to you in your research. My gut feeling is that it’s a good engine, however the if the extended warranty won’t cover the DEF and emmissions, it’ll be expensive to repair. Depending on the in service date of the car, you might get a total of five years, but probably closer to fours years of MB warranty, included extended.

Utlimately, it’s the DEF (diesel exhaust fluid) system that can be problematic over extended use. However, I don’t have any practical experience with 150k plus mileage on diesels...which should be easily achievable based on the design.