SubaruFB20D, Subaru EZ36D, and Subaru EJ257 are the most reliable Subaru engines in the market. The Subaru FB20D is a naturally aspirated engine with 2.5 and 2.0-liter displacement levels. They now have increased piston stroke and a decrease in the bore size, which enhances the engine performance and reliability 4 Low center of gravity. One of the most important benefits of a boxer engine is that it has a low center of gravity. There are many car owners who want their automobiles to be as low to the ground as possible, and this boxer engine is definitely their cup of tea. It raises stability as well as improves agility. RangeRover models seem to have a poor reliability reputation (deserved or not). I am sure a lot of people criticise them with no personal knowledge. Are there any specific Ingenium engines that are known to be good or bad. 4 or 6 cylinder, any specific year model. Diesel Heads does not give these engines a good review. Accordingto Bell Performance, Subaru, Audi, and Volkswagen currently sell cars with diesel engines in the United States. These engines offer improved efficiency over gas engines without using Dieselengines are known for being frugal and reliable, but certain engines failed to live up to expectations. 3 Subaru EE20 (2.0D Boxer Diesel) Subaru. In 2007, Subaru started a revolution by introducing the first ever diesel-powered boxer engine to ever be installed into a production car. Theboxer engine remained available for generations to come and it proved to be more than reliable, but there are some Subaru Legacy years to avoid. So, if you are considering buying this car, this guide will help you figure out the safest model years to go for. This is the time when Subaru struggled with diesel engines and the main problem SubaruCVT reliability . There is a fundamental issue that no one has ever made a reliable single speed CVT driven by an engine. Subaru could be the 1st to do it and the current 2020+ gen could be the 1st (after 3-5 failures depending on how you count gens,) but being the 1st you have to show it is good before people trust it. Dieselengine options cost more to purchase. Emissions systems require more servicing, which also adds to yearly costs. And diesel fuel costs more than fx6H.