While not directly comparable to cars elsewhere, I've driven the Ford Focus 1.0L 3 cylinder powered rental cars. They are slow, at about 10 seconds 0-60, despite 125 claimed HP, which honestly feels like about 80HP. Although top speed seems good, the 1.0 3 cylinder turbo is working hard at fast highway speeds found here in the states.
The 3 cylinder sounds really nice, and is smooth enough. But in my opinion, it's too small for American highways. And a full throttle request at 80MPH results in no perceptible acceleration and seems to take an eternity to gain another 5MPH. The reason I bring this up is that passing power is very lacking. Although the turbo does a good job at producing enough power for "cruise flight" in most conditions, including up mild hills.
I'd only consider a well tuned 3 cylinder engine in a light weight car.
I own one of these 3cyl focus and I can confirm everything. They're great for just setting the cruise control on the highway and leaving it but they lack any serious power if you need to pass on a 2-lane highway or go up a hill. Passing anybody on 2-lane highways require some planning, good visibility, and fast approach speeds. However, I know for a fact they're faster than a 4cyl-5spd fiesta and slower than a rental Hyundai Accent. A hidden gem with this car though is the 'overboost' function; I think it gives around 6PSI more boost if you're flooring it and will stop the extra boost when you start easing your feet off the throttle.
An example, on I-70 going through the rockies will require me to drop down to third or fourth gear and floor
the throttle in order to not drop under 60mph.
On the plus side, there's lots of space in the engine bay, it's easy to work with, and the starter is easily accessible at the rear of the engine from underneath - you only have to take off the under tray to get to it. You can drop the trans without the subframe in the way too.
I imagine they're great for Europe considering our neighbors across the pond's smaller roads although overall this engine does not belong in a 3000 pound car. A prius, corolla, civic, Mazda 3 and just about any other compact car gets very similar gas mileage but doesn't feel like you're dragging around a battleship's anchor (although the 1.0L was great when it was introduced in 2012.)