Your question can't be answered as asked. If you rephrase the question to read simply "What makes the 5th gen 4Runner reliable?" then that answer is fairly simple:
Toyota simply has engineered their product to function longer than most of their counterparts with fewer problems.
You can't assume that performance is compromised in any component that Toyota did not decide to use. I mean, can your really say that a six speed transmission is higher performing than a five speed? In some cases a five speed is not as reliable as a six speed. It just depends. What is your criteria? Efficiency? Ease of use? Complexity? Cost?
Every single vehicle manufactured is a compromise in some shape, way or form. A Ferrari is not the ideal way to move people from point A to point B. Neither is it the best vehicle to go rock crawling with. A 4Runner is not the best track day vehicle nor is it the most fuel efficient.
Our 4Runners are a very reliable SUV with a robust design capable of going off road at a median price point. The whole package is what makes it reliable, not any specific component.
