how long is a piece of string?
will depend on how it is driven. high speeds and poor servicing for example reduce lifespan.
surroundings play a part eg left in open through winters.
mechanically everything can for a cost be replaced.bodywork is where it suddenly goes really rusty and becomes totally uneconomic to fix.though essentially even this can be replaced.
engines will last longer on long straight runs rather than in heavy traffic and hilly areas. average life expectancy is around 1800.000 miles.
That car will last forever. I almost bought a 1990 300e. It has 250,000 miles on it. Instead, I decided to buy a 1998 C230. It has 192,000. Just make sure u do regular maintance!! Oil changes, tune ups, replacing bellts and hoses, etc. Make sure all fluids are at the proper level at all times. These Mercedes last forever