...sounds like you'd benefit with peace of mind most from having a qualified tech actually review these critical areas on your vehicle then afterwards review findings with you

if you do not have maintence records for your car- - now is the time to establish a good maintence and record program

>oil & filter changes
>coolant and hydraulic fluids
>alignment/ tire balances
>15k, 30k services
>etc.

though robust, the 500e requires maintence as all MBs do to provide the best motoring experience

...don't think its common for a 500e needing a couple of quarts of oil to 'smoke' or overheat...if you added a couple of quarts of oil when the stick was at 1/4--- keep in mind that there is still about 6 quarts in the sump (1.5 gals)- - so its not entirely dry>>> if you're using oil between changes (enough to require a couple of quarts), this may be a sign of worn valve guides and you may wish to address it

keep a close watch on the oil usage and on the temp gauge....a through inspection is in order from a qualified 500e tech

-fad