What is the difference between 2-pole and 4-pole motors?

Essentially the higher the number of poles equates to the motor running at a lower RPM / speed to generate the same amount of flow. Therefore a 4-pole motor is better than a 2-pole motor which translates to lower operating speeds which then generates less noise and has a longer duty cycle when compared to a 2-pole motor.

What's is the optimum pressure rating required to wash my car?

Generally you do not need such high pressures for the purposes of washing your car as it can also damage your paint if it is too high and where the pressure point is concentrated on a small spot. The ideal operating pressures at the outlet of the gun is between 950-1300psi. 

What is the difference between induction and synchronous (universal) motor used in pressure washers?

The fundamental difference between these two motors is that the speed of the rotor relative to the speed of the stator is equal for synchronous motors, while the rotor speed in induction motors is less than its synchronous speed. This is why induction motors are also known as asynchronous motors.

Are pressure washers with inductions motors better?

Induction motors are simple, rugged in construction and are therefore quieter and more robust than universal motors. However they are usually heavier and more expensive which is why they are more commonly found in commercial or higher grade pressure washers.

Are the inlet and outlet adaptors for all pressure washers universal?

This actually differs from brand to brand and therefore there isn't a standard or universal fitting across brands like Karcher, Gerni, Bosch and Kranzle. It is best to check with our customer support team to ensure you have the right fitting to make an accessory work with your pressure washer.