Ford 2013 C-MAX HYBRID Owner's Manual page 189

188 Unique Driving Characteristics
Question
Why does it take
a long time
before the engine
shuts down?
Why does my
engine never
shut down
above 60 mph
(96 km/h)?
Why does my
engine stay
on when it's
extremely cold
outside?
Why does my
engine rev up so
high sometimes
when I
accelerate?
2013 C-Max Full Hybrid (34h)
Owners Guide gf, 3rd Printing, January 2013
USA (fus)
Answer
There are several reasons the engine stays on for an
extended amount of time when it is first started.
One common reason is to ensure that the emissions
components are warm enough to minimize tailpipe
emissions. As the climate gets cooler, this engine-on
time is extended.
The engine is required to turn on above this speed
to protect the transmission hardware. (For C-MAX
Energi vehicles, you can travel up to 85 mph
[137 km/h] in EV mode.)
In order to ensure 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 minimum temperature.
(For C-MAX Energi vehicles, this is not required to
maintain cabin conditions.)
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
during steady state driving. These are
characteristics of the Atkinson engine cycle and the
eCVT transmission technology that help maximize
your hybrid's fuel economy.