Mechanical systems from the 1950s, ‘60s and ‘70s have either been augmented or replaced by electrical ones, adding layers of complexity to engine maintenance and repair. The silver lining is, in most cases, increased reliability – and not just fewer-oil-leaks reliability, but 100,000-miles-between-tune-ups reliability.

This writer knows first-hand, considering his car travelled more than 220,000 miles before requiring any major engine work.

To find out what might be most responsible for driving improvements in engine reliability, we took to Quora.com, the online question and answer forum, to gauge users’ thoughts.

Rise of the machines

In the past 15 or 20 years, control modules, sensors and on-board diagnostics have all contributed to improved engine function. Quora user Chris Leinbach thinks the switch to more computerised engines, with fewer mechanical systems, has had the "biggest impact on engine reliability".

He wrote that until the 1970s, an engine's reliance on mechanical systems required it to warm entirely through before it ran optimally, and its various headers and valves needed regular adjustments – usually with a wrench. "Now we have computers that are adjusting things as complex as valve timing in the engines in real time," Leinbach wrote.

Laury Curran argues that electronics plays an outsize role in engine reliability as well. He cited sophisticated algorithms that control factors such as fuel usage and ignition timing. "Engine management systems rely on a whole host of electronic sensors to control how much fuel is used and when," he wrote.

But computers haven't just increased engine reliability; they've altered how engines are built. Curran went on to note how engines are designed with three-dimensional computer models, which – with the help of digital simulators – can better target potential stress points and hot spots. "When it comes to testing in real time, the engines very often perform as designed and only minor changes need to be made before mass production starts," he said.

What the data says

But are the views of Quora users borne out by vehicle reliability data? Broadly speaking, yes.

According to JD Power and Associates' annual Vehicle Dependability Study, which has been conducted for 25 years, vehicle reliability has been on a sustained rise in the US, save for a blip last year.

In its 2014 report released in February, JD Power said there was an increase in owner-reported problems for 2011-model-year vehicles compared to the previous year, marking the first increase in reported problems in 15 years. The firm collected more than 41,000 survey responses from original owners of 2011-model-year vehicles after three years of ownership. Most of the problems, the survey authors noted, came from cars with four-cylinder engines.

While drivers can assume vehicles are more reliable than they were in the past, technology is no catch-all defense, and an engine’s sophistication creates an entire subset of new problems. That said, buyers can assume that a new car’s engine, at any price point, was born to run.