Before I proceed, I would first put some disclaimer here as I am not an expert on this area and I am not trying to provoke anybody. I only got this information from chatting with my in law, who use to sell car before he got retired.
So, this is my reply to your question Supersonic..
1. Why do businessmen favour diesel car over petrol for business tool and long term use? I think fuel price almost the same now.
RON 95 & diesel shares the same price but for the same full tank, the diesel car will go LONGER miles. The 523i will run for about 650km while the 520d will run for about 950km on extra urban consumption.
2. Why do businessman sell their diesel car after 5 yrs and replace again with newdiesel car? Dosent these also apply to petrol cars
I do agree with you that it applies to petrol car too as it will be some headache to maintain a car after 5 years. But, If somebody came to you now and offered you a 5 years old 4 cylinder turbodiesel BMW and a 5 years old NA 6 inline petrol BMW for about the same price, which one you would want to take?
Businessman would normally do a lot of travels and its economical for them to have a diesel engine car. They will lenjan or get the "value" of their car because they normally travels longer miles for their business purpose. They will sell it after 5 years as cars would normally give problems after that period and after all, the car has also been consuming the lower diesel quality in Malaysia too...
3. How do u know diesel engine will sound louder after a few yrs more than petrol engine. Any evidence on these?
Im afraid that I don’t have any evidence for this because it was only based on my informal chatting discussion with my father in law. Worth to mention that he used to sell cars before and FYI, he also considered buying the 520d too but decided against it after speaking to his friend who used to work with BMW Malaysia.
Just to share, my in law suggested me to get a 6 cylinders diesel if ever consider buying a turbodiesel engine. From his opinion, there might be some concern over the reliability of the 4 cylinders turbodiesel engine over long term period. The engine would be forced to do extra work to carry the F10 over a long time. Think about the forced induction of a 4 cylinder turbo engine needs to carry over a long period, what would happen? Push push push what will happen? Thats what he said... I am not sure about the reliability of this information but I did put a disclaimer up there?
I do envy the efficiency of the diesel engine though but I am just not so sure where are we at now with the current diesel being offered in Malaysia.
But I guess, for my first bimmer, its allright to have the NA engine before they vanished soon..
http://www.bmwblog.com/2011/04/15/are-you-going-to-miss-the-big-six-engines/