Side by side
| | Kärcher K1700 Cube Pressure Washer | Sun Joe SPX3550 Brushless Induction Pressure Washer | Active 2.0 Electric Pressure Washer |
|---|
| What it is | Cold-water electric pressure washer | Cold-water electric pressure washer | Cold-water electric pressure washer |
| Published output | 1700 PSI / 1.2 GPM, CETA certified | 2350 max PSI / 1.8 max GPM (2000 / 1.1 rated) | 1800 peak PSI / 2.0 GPM |
| Size / what ships | 16.3 lb, 0.3 gal detergent tank | 20 ft hose, 40.6 fl oz detergent tank | 20 ft hose, 35 ft GFCI cord |
| Best for | Small garages, and anyone who wants a verified number rather than a peak | Buyers who care about motor longevity and noise as much as output | Anyone who bought a pressure washer specifically to detail cars |
| Price band | Mid | Mid | Premium |
Every figure above is read from the product listing on the date recorded under each write-up below. Where a maker does not publish a figure, this table says so rather than estimating one.
The only number that is comparable is the rated one
This is the whole comparison, so it is worth being precise about it. A pressure washer has two output figures and manufacturers are free to quote either. A max(or “peak”) figure is what the pump can hit momentarily, typically at the instant the trigger closes and under no real load. A rated figure is what it holds while you are actually washing something. They can differ by a lot.
Pro Tool Reviews has made exactly this point about the category’s headline claims, bench-testing units against their PWMA-certified rated performance rather than their “PSI Max” stickers. Kärcher sells the K1700 on a CETA certification, which means an independent lab verified the claim; Sun Joe, to its credit, publishes both sets of numbers for the SPX3550 rather than only the flattering pair.
So line them up properly:
- Kärcher K1700 Cube: 1700 PSI / 1.2 GPM, certified. There is no second number.
- Sun Joe SPX3550:2350 PSI / 1.8 GPM max — 2000 PSI / 1.1 GPM rated.
On pressure, the Sun Joe genuinely wins: 2000 rated against 1700. On flow, the Kärcher wins by a tenth of a gallon a minute. And for washing a car, flow is the figure that matters, because flow is what carries soap onto the panel and rinses it off again. Pressure, past a surprisingly low threshold, is just risk you are carrying around.
Why flow beats pressure on a car, in one paragraph
A foam cannon works by forcing water through a small orifice and pulling soap into the stream. Starve it of water and you get a thin, wet soap mist that runs straight off the panel. Feed it and you get the thick clinging layer the whole method depends on, because the dwell time of that layer is what lifts grit before a mitt touches the paint. Rinsing works the same way: volume sheets contamination off, pressure just concentrates force on a smaller spot. Our pressure washer roundup sorts the whole category on rated GPM for this reason, and what PSI to use on a car covers the other half of it.
Where the Sun Joe genuinely wins
The motor. A brushless induction motor has no brushes to wear, runs cooler and is audibly quieter than the universal motor in most machines at this price. If you expect to own this thing for a decade, that is a real argument, and it is not one the Kärcher answers.
The tank.40.6 fl oz against 0.3 gallon (38.4 fl oz) is close on paper, but in practice the Kärcher’s small tank is a known annoyance on a full-size car — it runs dry mid-wash. Neither tank is a substitute for a proper foam cannon; both are for the onboard detergent siphon, which produces soapy water rather than foam.
Nozzles.The SPX3550 ships five quick-connect tips and a total-stop system. One of those tips is a 0-degree pencil jet, which should never be pointed at bodywork under any circumstances. The Kärcher’s bundled turbo nozzle deserves the same treatment. Kärcher’s own car-wash guidance is explicit: “Always wash your car with the flat jet and not with the rotor nozzle”, keep a minimum distance of 15 centimetres from the surface and 30 centimetres from tyres, and work from the bottom up.
Where the Kärcher genuinely wins
It fits on a shelf. 16.3 lb in a cube body is the single most underrated feature in this category. A pressure washer you have to drag out from behind the lawnmower is a pressure washer you stop using. The Sun Joe is a wheeled frame; it lives on the floor.
The number is verified. This matters more than it sounds, because it means you can compare the K1700 to another certified unit and get a real answer. Most of the category quotes uncertified max figures that are not comparable to each other, to the Kärcher, or to anything.
The warranty. Three years, limited, from a manufacturer that has been making these since before the category had a US retail presence.
What neither machine changes
Both of these run on a standard 15-amp household circuit, so neither can exceed what that outlet supports — which is why no electric washer in this price band produces both high pressure and high flow. You are choosing which side of that budget to spend. Both ship a 20 ft hose, which means repositioning the unit once partway around a larger vehicle. And neither one washes the car: the two-bucket contact wash does that, and the machine only handles the pre-soak and the rinse.
If what you actually wanted was the complete setup rather than the machine alone, the six pieces of a pressure-washer wash and which fittings have to match are set out separately. And if you are still deciding whether to buy a machine at all, read pressure washer versus garden hose first — for a lot of people the honest answer is that a hose and a good bucket wash gets the car equally clean.
Our call
Between these two specifically: Kärcher K1700 Cube for a car. Higher rated flow, a certified number you can trust, and a body that stores where you will actually reach for it. Sun Joe SPX3550 if the brushless motor and the bigger tank matter more to you than a tenth of a gallon per minute, or if you want the extra pressure headroom for a patio.
And the answer neither brand gives you: if the point of the purchase is foam, spend the extra on the Active 2.0. 2.0 GPM rated against 1.2 and 1.1 is not a marginal difference — it is the difference between a cannon that works and one that disappoints you every Saturday.
