This is possibly the most off-topic post I have ever put on LIM, but this tip proved so useful to me that I thought I would share it.
I have a leak in my car which is causing the floor behind the driver's seat to become very wet. This kind of problem is not easy to fix, but the first issue was a huge amount of condensation in the car when it is cold overnight.
After some searching, I found a tip which is to put some cat litter in a sock and under one of the seats. Remarkably, I have had no condensation in the car at all since even when all of the other cars in my street are badly affected in the early mornings. Apparently this works particularly well when the car has frosted, but you should change the litter every 3-4 days in the coldest times. You can then brings the old litter in and let it dry in the bag in the house and use it again a few days later. A £2 solution which will save you a lot of time in those horrible Winter mornings and it will potentially keep your car interior in better condition.
Any random tips you would like to share with the rest of us?