I don't doubt what you say, what is BS is anyone saying "you can't make an engine that lasts X thousand miles/hours and that meets emissions". Now if he had said "that lasts X thousand miles, meets emissions, has a specific power of Y as expected by the target market and costs less than Z" then I would have heartily agreed.
There are after all any number of absolutely enormous engines powering ships and delivering thousands of BHP for thousands upon thousands of hours without incident. I'm sure that they could be made to meet emissions. But you don't want to be paying the cost.
I agree with most of what you say. The Mercedes statement was by its nature brief and general. Car companies are getting squeezed from both ends. Consumers want more gadgets at less cost. Fleet managers want low running costs over large mileages. The former dictates cheap short lived components that support the gadget proliferation and maintain selling price. The latter demands better quality higher cost components.
The ship engine analogy reminds me of an aero engine analogy
. Whist working as an Engineer in a car plant a manufacturing facility suffered a bearing failure, in the space of two hours the bearing went from running fine to welded to the shaft it supported. To their credit Maintenance got the plant back up and running in 8hrs. But this was in a company with 6,000 staff on site doing nothing for 8hrs, estimated running cost back in the mid nineties was £8,000 a minute including energy. In the postmortem the Maintenance Manager stated that it was not possible to detect bearing demise quick enough to prevent failure in service. The MD paused from swearing his head off, breathing deeply, allowing his eyes to stop bulging and his veins to recede back to their normal state, exclaimed "I don't accept that, otherwise planes would be falling out of the sky every day".
They were both right. With continuous monitoring equipment and alarm systems bearing failure could be predicted before catastrophic failure. However there are literally hundreds of thousands of bearings, motors, chains, belts, cylinders etc etc in a car plant, any one of which will stop the whole plant dead for many hours or days. The cost to fit and maintain effective continuous monitoring systems to that inventory of critical components would torpedo any hope of the plant ever making a profit again. But the Maintenance Manager knew better than to explain this, unless you want a short and pain filled career you take the beasting.
Contrast that to marine, my neighbour, a ships Engineer: "we change everything once its clocked the prescribed number of hours whether its showing signs of failure or otherwise".
Profit margins are slim in mainstream automotive, it can't employ the cost no object maintenance strategies of other industries such as marine. If someone offered a car for sale that never broke down nobody would buy it because the cost to build and and maintain it to the required standards would be unaffordable.