Although using hot water to wash your car can be more comfortable on your hands, it can also be unnecessary hassle. For example, not all kitchen sinks provide enough space to get the buckets under the tap and you also have to carry the bucket through the house, which may cause water to drip. Therefore, this brings us to the discussion of whether or not you should wash your car with hot or cold water and if it even makes a difference.
Benefits of Washing With Hot Water
- More comfortable on your hands (particularly in cold weather)
- Helps to improve the performance of some shampoos
- Can help to remove stubborn dirt more easily (such as bug splatter and tar)
- Increases the foaming abilities of the shampoo
Benefits of Washing With Cold Water
- Easier to access (unless you have a hot water outside tap)
- Uses less energy to heat the water and doesn’t require additional equipment
- Cools down the surface when washing your car in the summer
- Doesn’t effect the waxed surface or oils if a car wax has been applied
Type of Shampoo Used
Depending upon the car shampoo you use to wash your car may determine whether or not you need to use hot or cold water. For example, some brands state that hot water must be used in order to improve the performance of the shampoo as its being mixed with the water.
If you intend on using a snow foam, the majority of brands state that hot water must be mixed inside of the lance. Failing to do so will effect the ability of the car pressure washer to output thick foam that clings to the car as the water mixes with the snow foam solution.
Therefore, you may not have the choice and will need to use hot or cold water determined by the instructions on the shampoo bottle that you use.

Conclusion
As you can see above, using hot or cold water to wash your car comes with their own benefits but it’s highly dependent upon the shampoo used. In short, if you want to keep your hands warm and ensure the shampoo gives you maximum cleaning power, you should use hot water to wash your car.
However, if access to hot water is a pain and you don’t want to effect the performance of any waxes applied, cold water straight from the hose pipe is perfectly fine. There really is very little difference and its a matter of personal preference.
Personally, I use a mixture of cold water from the hose pipe that’s then topped up with a boiling water from the kettle. This produces “luke warm” water in the bucket. The main reason for this is due the fact that placing the bucket underneath the tap is near enough impossible. However, eventually I intend on installing a hot water tap outside where I clean my cars.