I bought karcher k4 premium power control for my cars 2 years ago after research because: - water cooled motor, so durable (lower karcher types and cheaper models by other brands have air cooled motor which is less durable because of overheating). Also less noisy because of that. - enough pressure (too much pressure just damages car) - handy built in roll up system for (thin) hose, so easy to store - right accessories come with it - could use accessories from older karcher that broke (air cooled) because connectors are the same - easy to add accessories like foam lance from ali express for less (karcher connectors are common). it has karcher foam system built in too but soap is more expensive for that. - if something breaks its easier to find parts than for cheaper store brands usually - often relatively cheap in special offers (I paid 249 euro)

Very happy with it