Should I get a MHEV or not?

I’m in the market for a BMW g20 320d because I do a lot of motorway miles, at least 200 miles on the motorway a week.

My current car tends to spend most of any journey I make with the cruise control set to 70mph, I don’t do a lot of city driving or driving at lower speeds.

I know that having a diesel is the perfect car for the amount and type of driving I do however, I’m not sure whether getting the mild-hybrid version of the car is worth the extra money or not.

I’ve been told that it works as an improved start/stop system that only helps the engine a little bit but can do wonders for fuel economy.

Will my fuel economy really improve that drastically that I should consider spending another £1,500 or so on the MHEV version?

I was also wondering if having the MHEV version of the car would prevent me from getting an eco remap on the car as this is something I’ve thought about doing for a while.