Reliability often gets thrown around as a vague term in the automotive world, even though it shouldn't be because a select group of four-cylinder engines earned that reputation through decades of hard proof and not just "word of mouth" alone. These are the four-cylinders that mechanics recommend without a second thought, the ones still running strong at six-figure mileage, and the ones that keep going even when their owners ignore them. However, what ties these engines together is consistency: fewer weak points, forgiving build tolerances, and manufacturers who clearly prioritized longevity over chasing performance. On the modern end, several newer engines have shown that turbocharging, direct injection, and stricter emissions rules don't have to come at the expense of reliability. With that in mind, here's a look at some of the most reliable four-cylinder engines ever built and what it actually takes to keep one running long after most engines would have given up.