How about a block heater for that purpose? I think it is more useful than a butt heater
Mercedes has water pumps that are deactivated until reaching a certain temp. There are a lot of things going on to decrease the amount of time it takes to reach operating temp mostly due to emissions and fuel economy. A cold engine consumes more fuel than one at operating temp.
2014 Mustang V6 3.7L 6-spd manual, with MGW shifter, Airaid CAI, BBK shorty headers, Corsa Sport axle back, strut tower brace, JLT oil separator, GT500 differential cover, BG Synchro Shift II gear oil, Redline differential oil.