Hey Dude...
First of all its nice to hear that you love BMW's... But if you love them so much, why would you want to buy BMW with a Corona Engine...??? The whole point of buying and loving a BMW is lost right there... its not only the good looks, but its also about the power, performance and superior technology.
Secondly it doesnt matter if the vehicle is a 19 - XXXX or a english number... I bought a E30 316i which is a 16-XXXX and it does great on fuel, its trouble free and most importantly its a comfortable and safe drive... I would never go back to a Jap car ever again
The most important thing about buying a car is being patient my friend, coz you get only one chance and you need to make the right choice when you do... You really dont want to end up with a crappy car that sits in your garage or in a mechanics shed... Trust me you will regret your choice and it'll be too late, coz it wont be easy to part with it. It took me nearly 6-8 months to find the right BMW for me (Im no rich kid, I had to save up and find a car that suited my micro budget ), but now im enjoying the outcome of my sacrifice, coz Im driving my dream car and I have no issues to deal with.
Ask yourself the question why is this guy selling a BMW for 500k??? Would you, if it was your car... Also try to find out who maintained the car, the number of owners and it's mileage... when buying a Euro car, its always good to know its history...
I really do hope you make the right choice, coz eventually it is your call so all the best mate, hope you find the right car at the right time.