Toyota 2GR-FEDid you really think we could talk about the most reliable engines without mentioning Toyota more than once? Of course not. Toyota's list of super durable powertrains is far too long and expansive, but one we just had to single out is the 2GR-FE 3.5-liter V6, seen in Camries, Avalons, and even the Lotus Evora.The 4.0-liter 1GR-FE unit did suffer from a few somewhat significant issues, believe it or not, but that is not the case with the 2GR-FE. The 2GR-FE wasn't safe from a few minor problems, as they had a tendency to leak oil through the front timing cover. However, if you take care of this issue quickly, you'll have quite a reliable companion on your hands.These engines are pretty low maintenance, and if you do the little maintenance they require regularly, they can easily go for hundreds of thousands of miles. The Camry is the most notable application for this engine, and you already know about the indestructibility of that.Jeep 4.0 I6The Jeep 4.0 I6 is a bit of a wildcard. Jeep isn't exactly known for quality or reliable powertrains. Some of you might have seen that fake news report claiming that Jeep has threatened to continue building cars, which should make it clear how most people feel about Jeeps. Up to 30 years ago, however, things were a little different.For a while, you could have a Jeep with a 4.0-liter gasoline six-cylinder engine, jointly developed by Jeep and the American Motor Corporation, Jeep's last owner before it was scooped up by Chrysler. Obviously, this engine went into all types of Cherokees and Wranglers throughout the 80s, 90s, and into the early 2000s in some cases.Jeep owners and the Jeep community in general absolutely swears by the 4.0-liter six, due to its incredible reliability and its ability to take a beating. Remember, Jeeps do take a beating because of their off-road capabilities. Similarly to the LS V8, the 4.0 I6 is a simple affair with overhead valves instead of camshafts, and Jeep owners frequently report anywhere from 300,000 miles to half a million with regular, proper maintenance.