If I don't warm up my car in the mornings the windshield gets so foggy that I can't see.
The Heat/AC doesn't seem to help fast enough, and wiping the windshield leaves streaks.
How can I deal with this quickly so I can get back to driving safely?
Since the fog comes from moisture inside the car a simple solution is to dehumidify the car by filling an old sock with kitty litter and placing it inside the car in an inconspicuous place like under a seat. You might want to use an old pair of socks and double wrap the kitty litter.
Video from Huffington post of the kitty liter trick
But did you know there's a super easy way to beat motor mist?
Simply put some cat litter in a sock, leave it in your car and you'll be on the road without delay every time.
The fog comes from water condensing on the windshield or windows. The problem is that the air inside the car is warmer and/or wetter than outside. (e.g., https://van.physics.illinois.edu/qa/listing.php?id=1511)
One of the faster ways is to lower your windows to lower the temperature in the car, and decrease the humidity by bringing in outside air. This may not be particularly comfortable but it definitely works.
If wiping leaves streaks, then there is something on the glass (oils from wiping with a rag that isn't perfectly clean etc) so it will not get better until properly cleaned.
You need to really give your windscreen a good clean, and then use a product like Rain-X's window defogger (it's a window cleaner with something else that prevents condensation) - and it will last for months (possibly years - not sure)
Also, using aircon helps to dry out the air in your car, reducing the problem.