New car

Should I but an altima or Mercedes 300 awd

Is the amount of money you have to spend a factor? If yes, the Altima will be almost as comfortable, fast enough, and much less expensive to maintain and repair.

If you have plenty of bucks and prestige and image are important to you, why not a Mercedes? Just be ready to pay about 3X more for maintanence and repairs on the MB if you go that route.

You should buy neither. You should get a bicycle. You will get a lot more exercise and save a lot of money.

Buy the one you like. Maybe the best car for you is a Smart Car. We don’t know enough about your needs and desires to come close to making a suggestion.

If you have a concern, tell us about that.

Both do an excellent job at the basic needs of an automobile.

Honestly its personal preference. The upkeep of a MB is far greater than a altima unless you keep only during their free maintenance period if any.

How much are you willing to spend per year on repairs and servicing? The Benz will have significantly higher maintenance and repair costs that the Nissan.

new? used?
Both are completely different animals. one is FWD, the other is AWD. one has a 3.5L v6 matted to a CVT, the other has a 3L v6 matted to a 7 speed automatic.