My 1974 W115 240D automatic is the real speed demon! It does a grand speed of 78 mph but you have to hold it wide open for at least 2 1/2 to 3 miles to attain that speed. 74 is easy, getting that extra 4 mph is the hard part!~ A bit of a wind not in your favor then you can forget anything over 74-75 mph! I swear a bicycle could beat it up to 20 mph! Pulling out into traffic takes real guts! And Bravery! And you hope the other person has good brakes!
That W123 240D will beat it with ease!
As for 50's technology, look at the Ford 7.3 Liter diesel, it was originally a International engine designed in the 50's and it is still basically the very exact same engine.
As for comparing truck engines to the car enine, it is Still The Same principal - a diesel engine is a diesel engine - it functions the exact same, irregarless whether it is in a car or stationary or in a truck or a dozer.
The basic function is still the same. Whether it is a 4 stoke or a 2 stoke, it still functions and worked the same way, and it doesn't matter if the diesel engine was designed in 1930 or 2002. It take Air and fuel and compression to make it work.