Complex sentence: Between reducing the pumping losses, which increases pressure in each operating cylinder, and decreasing the amount of fuel being pumped into the cylinders, fuel consumption can be reduced by 8 to 25 percent in highway conditions.
Split into simpler sentences: Between reducing the pumping losses which increases pressure in each operating cylinder and decreasing the amount of fuel being pumped into the cylinders. Fuel consumption can be reduced by 8 to 25 percent in highway conditions.