No need for that. The ingredients for having a 6km drive to the...

No need for that. The ingredients for having a 6km drive to the workplace count as a 20km drive are as follows:

• Temperatures between 0° and -10°
• No garage, no preheating
• The natural urge for a car heated at least up to 19° whilst driving

That is all you need to third your range. If temperature gets over 3°, it will be only half then. For a longer drive, it will be different as heating wont kick in that much, but I am still not willing to move my work place further away or put my car into my bedroom ;-)