Well, if you're retired I guess you dont need to worry about reliability or office commuting on a daily basis.. So if you want to just enjoy a Mercedes go for it. Clearly you aren't buying it with rupees and cents in mind (if you were you'd still be driving a toyota)
Just go for it, but be aware that ownership wont be as economical as a toyota, but you'll enjoy it a LOT more than a Toyota.
You probably know that the car's huge, right? Alternatively you can look at a W210 which would be a bit newer, a bit smaller and a bit cheaper to own/run. Plus i think there's more vehicle's in the market so you can be a bit picky.
Good luck