I love a tow car question. You’ll have Discovery 4 and Nissan Navara in your short list before the night is out!
6.5m and 150hp will be a braked trailer. From what I can see a Mercedes E220d will haul 2100kg.
Boat from what I can determine is 580kg dry weight, and max plated transom up to 200kg for engine plus trailer of course. Mercedes is rear wheel drive too with 9-speed auto box. Read a few other threads whether tow is factory fit or retro. Factory fit has some sort of cooling built in, for extreme temperatures.
https://www.caravantalk.co.uk/commun...d-as-a-towcar/
Just back after a week in the sun in Lefkada, Sivota Bay, Greece (no boat). I swear that hire car will never be the same. Very hilly, temperatures of up to 25 degrees. Can only imagine if you were hauling in the height of summer and watching the thermostat. They are very lucky in the respect Ionian Sea is not tidal.
So here’s the thing. Maximum nose hitch weight is 85kg. That’s not unusual. For most avant/estates (I’m making an assumption here) then it ranges from 80-85kg. Something to be aware of, as most will be rear coil springs.
Then the tricky question. Is it just hauling and launching on concrete slips? If algae laden green slips, then use a rope to launch and recover. If you need to venture onto sand, then beware. This is where 4WD will sort the wheat from the chaff.
You don’t necessarily need to go down SUV route if you feel Merc isn’t up to it. I’ve been driving Audi Quattros for years. Currently in A4 3.0TDI V6 Allroad. Pulls like an Amtrak.