Are there ferries in the world capable of crossing Atlantic Ocean with passengers and cars? For instance btw Le Havre (F) and Boston (USA). I think that ferries navigating btw UK and the Continental Europe including Scandinavia are not suitable for transatlantic cruise. Are there ferries operating at another part of the world but could handle this route? If yes, can these ships cross the Atlantic in about 5 days? Did anybody or company tired this in the past? My research so far did not provide clear answers to these questions.
Yes, such services exist.
You can either ship your car inside a container, (or half container) in which case it goes onto a container ship, or you can use a RORO (roll on roll off) ship, in which case the car literally drives on and off the ship at either end.
Some RORO services will allow you to sail on the ship with the car.
In either case you should expect a crossing between Europe and North America to take about 5-15 days depending on which specific ports you travel between.
Recommending specific services isn't something we do here, so I won't link to any specific provider. Try search terms such as
roro usa europe.