My Beetle does not warm up until I start driving it, WHY?

Thermostat.

start it for 20 min then check the oil level Check if the exhaust is leaking that's another problem

If you live in the Continental Climate of Praire Canada this is a typical problem with the 4 cylinder gas or diesel engine under 2.0L. YOu have to bundle your engine compartment with a winter front, a 190 Degree F thermostat and coving up of all the holes leaking cold air in you engine compartment. These aluminum engines only consume .9L per hour when warm during idle. I have an oil stove that burns faster than that. Wrap it up. Get the operating temperature up otherwise you will experience condensation in the crankcase oil which causes sludge in your oil just like those funny castrol commercials.

It's a 2004 - the water pump is worn or the idle speed is too low. When you rev the engine, more water flow through the heater core.

HI You cane check for low coolant first then check thermostat it cane b stuck open .If that not it check the water pump .The pump cane still b working but not good en off. you can all so take the rad cap off to see if the water is moving when the engine is running at idle then rev it up to see if it moves faster then it was on idle. PS b carefull when u take the cap off the coolant can b very hot .good luck

Be more than careful Simply do NOT pop a hot radiator cap, you are talking serious burn injury

Let see dedell, when you cane check as long as you don't scratch the paint.:(