Have to recall that SNS3Guppy has had his engine failures to nothing less complex than an IO540 if I recall his last couple posts correctly... If someone put an R2600 in a C172 I wouldn't want to fly it. How often have you heard of an O320, O360 or IO360 packing up when it wasn't due to fuel starvation or carburettor ice? Happens, but it's rare as hell...
I believe I also identified small 65 hp powerplants such as the A65 or C65 (J-3 Cub), and the 0-200 (Cessna 150). To be included as well are the 0-320, and O-470/U-470 (Cessna 182, Cessna 310). Point is, it happens, and when it does, how well anyone else has prepared for it is completely irrelevant to you. How well you're prepared for it is all that's important.
Preparation is as much mental and emotional as it is training to put the airplane in the dirt or in the trees or water. Having thought through it an mentally briefed and prepared for the situation is important, but even more so is the ability to not live in the past. The sensation of "this can't be happening to me" is a natural one. However, the ability to let go of what used to be, and live with what is, becomes one of the single most important traits you can posses when things get quiet, or rough.
I've done a lot of work on the side to support my flying habits, including various duties that required the use of a firearm. That in turn required regular qualification with the firearm. One job involved protecting large sums of money. One of the range qualifications involved holding a money bag weighted down to resemble coins and cash. It was held in the shooting hand, and on a signal, one had to drop the bag, draw the duty sidearm, and engage two targets with two shots to the torso and one to the head, each. The number of shooters who attempted to transfer the money bag to their other hand, or who attempted to draw with the bag still in their hand, or who did nothing because they couldn't mentally let go of that bag, was very surprising. Especially under pressure. Seems so simple...just letting go. It's not simple.
Letting go of what was, whatever that may be, is crucial to survival. Don't be jaded into thinking that because an engine is "simple" then it's foolproof, or less failure prone. It isn't. It may be the carburetor; I've seen floats stick, jets plug, carb ice that builds extremely rapidly and engines that can't be restarted as a result, cylinder heads that lift, valves that fail, propellers that break, magnetos that disintegrate...it happens, and can happen to you. A finely tuned and well running engine is wonderful, but you fly the wing, not the engine. Whether the engine is there or not doesn't determine your ability to fly the airplane...just the trajectory you'll eventually take and the range ou have available to you. The airplane is still the same airplane it always was, still responds to your control inputs, and is still under your control when you lose power. You may lose some of it, you may lose all of it. Whatever you've lost (even if the throttle is stuck wide open, or the mixture control has frozen...I've seen those too) or are stuck with...fly it.
The truth is that the IO-540 isn't really much more complicated than the 0-200 or 0-320. It's a slightly bigger air cooled engine with a few more parts...but basically the same. Any engine can fail. Unlike a car, however, you don't simply pull over to the side of the road.
As a PPL with quite a few hours but never an engine failure, it puzzles me why aircraft engines are prone to failing after all the controls and servicing when car engines with all their gadgets never seem to stop of their own accord these days. When did you last have the engine on your car stop dead - I haven't and I do about 30,000 miles a year?
I've had a few cars quit over the years. Mostly older cars, which I tend to drive. I've been through several vans, each over 200,000 miles, and each have had engine failures, and transmission failures during that time. I have a suzuki samurai that's between engines...just going in for it's fourth engine. It will probably be going long after I'm gone. But engines aren't infallible. I drive about 85,000 miles a year or so in my personal auto.
Many of my mile are highway miles. Long stretches of ten hours or more, regularly, when I'm home. The engine lives a fairly easy life; constant RPM, relatively low demand, and it's climate controlled; a cooling system which keeps the metal in that engine under fairly constant conditions. The engine and transmission are fixed in the vehicle with essentially only one type of load.
Compare that to an aircraft engine which is exposed to the environment, is cooled by changing airflow, is largely magnesium and aluminum, rather than steel, and in many cases is a direct drive crankshaft attached to a large spinning disc which is subject to gyroscopic forces, air loads, and a varietyof moments. The engine may fly through a rainstorm with changing cooling characteristics, or be taking off on a hot dry desert day. The engine may sit on the front of an airplane that merely takes off, keeps a fairly constant power, and lands...or it may be on the front of an airplane that maneuvers hard and puts a lot of stress on the engine, propeller, and airframe. Some engines live very hard lives, some don't.
An engine failure in a car doesn't have nearly the psychological significance as one in an aircraft. It's not nearly as memorable, either. The engine in your airplane has some significant differences from the one in your car...the biggest similiarity being that they both have pistons. Bear in mind that it's not just piston engines that fail, though.
Rather than getting too wrapped around the axle about car engines, perhaps it's best to think in terms of the potential to lose any aircraft system. It could be landing gear, it could be hydraulic, it could be a flight control, a flight instrument, fuel, an electrical component or system. An engine failure may not be nearly as significant as a failure of a different kind...your assignment as pilot in command is to ensure that the flight is handled safely regardless of what quits, malfunctions, goes awry, or doesn't quite work as advertised. It happens.
In the past month or so I had a hydraulic pump case split...the pump pressurizing our brakes. I had a flap assembly fail and nearly leave the airplane. I had a smaller turbine engine used to provide electrical power and system air, fail (auxilliary power unit). A part of the electrical system on one engine, a Constant Speed Drive unit, failed. Various other conditions occured, each in different aircraft, each at different times, each handled by a particular checklist. Each of these conditions presented certain limitations we had to live with, but none of them were the end of the world. Aircraft are mechanical by nature, and mechanical things break, wear out, or operate in a manner sometimes for which they weren't designed. These things happen.
In light airplanes, I've had flaps fail. A wing crack. instruments and electrical quit. The year before last, an inflight fire. Again, it happens. The common component, which has absolutely nothing to do with measuring one's anatomy (but everything to do with getting on the ground safely) is how you address each situation. Each one is unique. Each one has a procedure, each one is controllable, each one can be handled...by you. Knowing your airplane, training as regularly as you can, reading, playing out scenarios in your mind, looking for traffic, looking for landing sites, avoiding putting yourself in untennable positions such as extended flight over water or flight in the clouds in single engine airplanes, etc...all go toward providing a successful outcome for you.
Bottom line is, it's all on your shoulders. Car or airplane.