Assume conservatively 15 MPG mileage rate. Assume fastest you ever go will be 80 MPH. That means in an hour you would consume 5.33 gallons. (not bloodly likely that this will happen, but anyway). Assume fuel recirc rate is 300%, i.e. you push 3X as much fuel as you use through the system. 3 x 5.33 GPH is 16 GPH. Or 0.2666 GPM. Pretty low flow rate by most filtration standards, even if you double it.

Rgds,
Chris W.
'95 E300D