According to empegs web it says:
Environmental
Operating temperature range,
digital music mode 5 deg. C to 55 deg. C
Operating temperature range,
radio mode only -20 deg. C to 60 deg. C
Humidity, operating 10% to 90% RH, non-condensing
Humidity, non-operating 5% to 95% RH, non-condensing
Shock, operating 150G
Shock, non-operating 400G
Note: figures vary depending on hard drive type fitted. Drives are kept spun down as much as possible
during operation.

also, the FAQ says:
Q. I live in a country where it gets very cold outside during the night/winter.
How will the empeg Car handle this?

A. The operating temperature range of the head unit is from 5 degrees C to 55
degrees C, and the non-operating range extends down to -20 degrees C. If it
gets colder than this the unit can simply be removed from the car and taken
inside. This is the recommended procedure anyway, both for theft-prevention
and environmental control. A temperature sensor inside the unit ensures that
the hard disks will not operate outside the allowed range, although the
radio will.

/ gpf