Lincoln 2017 MKZ HYBRID Owner's Manual page 176

Why does my engine stay on when it is extremely cold outside?
Why does my engine rev up so high sometimes when I accelerate?
What is the fan noise I hear from the rear of my hybrid?
What is the engine oil change service interval?
Can I put E15 or E85 in my vehicle, and how will it affect my fuel
MKZ Hybrid (CC9) Hybrid Electric Vehicle (HEV), Canada/United States of America, enUSA, First Printing
Unique Driving Characteristics
Question
economy?
In order to make sure that the climate control system can begin heating
the cabin or defrosting the windshield as soon as a driver requests
it, the engine coolant temperature has to be kept sufficiently hot.
Keeping the engine on is required to maintain the correct coolant
Your vehicle's engine and transmission are designed to deliver the
power you need at the most efficient engine speed. This may be
higher than expected during heavy accelerations, and may fluctuate
when driving at a steady speed. These are characteristics of the
Atkinson engine cycle and the transmission technology that help
maximize your hybrid's fuel economy.
The fan noise comes from a fan located next to the high voltage
battery pack. This fan turns on when the battery requires cooling air.
The fan speed, and associated noise level, will change according to
the amount of cooling required to maintain good performance. Main-
taining the battery temperature at optimal conditions also prolongs
the useful life of the battery and helps to achieve better fuel economy.
Change the engine oil every 10000 miles (16000 kilometers) or once
per year under normal operating conditions.
Your hybrid vehicle can use E15 (15% ethanol, 85% gasoline) fuel, but
you may notice slightly reduced fuel economy because ethanol
contains less energy per gallon than gasoline. Your hybrid vehicle is
not designed to use E85 (85% ethanol).
173
Answer
temperature.