The Prius That Shook.. - VFAQ Prius Site

"Most of the test vehicles are unoccupied late at night or
early in the morning. We shouldn't have that much time to
let them sit idle. We should try to use them for testing on a 24-
hour a day basis, every minute of the day," someone suggested.
"Okay, we should start a 24-hour testing schedule."
Shinichi Abe made up his mind.
A seven-days-a-week 24-hours-a-day testing schedule was
announced. Every group established its estimated test
completion, and was expected to pass the test vehicle on to the
next group. When developmental work was at its peak in June,
July, and August, a Prius vehicle was constantly on the test
course.
In early June, a rumor started to circulate. It said that "a
ghost appears at the Toyota Head Office" and that people were
hearing whining noises at midnight. The stories started
immediately after the midnight Prius testing began.
The Prius prototype of that time emitted whining
sounds (from under the hood) when it was running only on
the electric motor.
Team members knew of the midnight testing, but
nobody else thought that a car was being tested because engine
noises were not heard. Even at midnight, the test course was
constantly crowded with six or seven Prius vehicles and that
resulted in a loud chorus of whining noises. A few people
were scared by the noise but some good came out of the late-
night testing. Because of the
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