The EPA tests include several parameters that seem out of step with how
most people drive: Air conditioners are never used; the average highway speed is
48 mph, never topping 60 mph (far slower than traffic flowed during PM's test);
and the city cycle averages 21.2 mph, never topping 56 mph. But here's the real
kicker: The EPA's city test schedule includes 23 stops and about 5-1/2 minutes
(out of 31) of idling. Since hybrid engines usually shut down during stops, this
parameter tends to exaggerate hybrid mileage results.