I have the timer set to turn on at 4:30 for a 7 to 8 am start. The timer are set to shut off at 10 if we don't leave early.
It is worth the peace of mind to ease the cold start strain too.

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1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily