Yes and no.

If you are keeping - driving the vehicle, and set a reasonable budget you can afford (and stick to it) = not for most people.
Note: There are many Happy owners/members driving a 240D - 300D with $28,000.00 total restoration cost, they consider what comparable car you can buy for that money today.


If you plan to sell it and recover all the money put into it, yes.
http://www.peachparts.com/shopforum/general-information/140433-could-i-ever-recover-what-ive-spent.html


If the car is truly special/rare pre-war or a valuable collector, different rules apply.

Mercedes 770 Großer - Google Search
1935 Mercedes-Benz 770 Großer Mercedes Pullman-Limousine - YouTube
1937 Mercedes-Benz 770 "Großer Mercedes" offener Tourenwagen - YouTube

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