What can comfortably carry a 220-pound person at 18 miles per hour then fold down into a package small enough to fit in the trunk of practically any car?
A folding electric scooter, that's what. And the S2 Booster from E-Twow, marketed as Uscooter in the US, is our favorite so far.
For starters, it's one of the few compact folding electric scooters with built-in headlights, taillights and a piezo horn so drivers can spot you in the dark.
The 500-watt front electric motor doubles as the scooter's primary brake, and triples as a way to top up the battery with regenerative braking! Perhaps that's why it had miles more range than other scooters we tested.
The top-mounted computer tracks your speed and mileage (or kilometers), and even offers cruise control.
Here are the handy brake (left) and throttle (right) levers. There's also a power switch and buttons that control the horn, turn off the lights and clear the trip counter.
This scooter has an all-important suspension system that lets you ride on the street -- not just the sidewalk -- without your teeth chattering. Not all of its rivals do. Here's the rear coil spring.
And here's the front damper.
Here's what the scooter looks like when it's fully closed -- nice and compact. It'll fit in the back of a Mazda Miata no problem, or a commuter train's overhead luggage rack.
The handlebars fold right down and lock into the rear wheel's fender.
Unfolding is a cinch. Just flip open the quick release lever, pull up on the handlebars and the spring-loaded pieces lock right into place.
Folding isn't quite so easy, unfortunately. You've got to master your heel-toe action to tap this tiny red pedal.
Another good reason to learn the heel-toe trick: When partially folded, this scooter can stand on its own.
This 23.8-pound scooter isn't light and most of the weight is near the front. You won't want to carry it around for long.
The wide deck gives you enough room to ride with two feet sideways, but you won't fit one in front of the other.
Close-up of the front wheel. The fenders aren't quite as large as I'd like -- some water tends to hit me in the face when I ride in the rain.
The rear fender doubles as an emergency friction brake that can contact the rear wheel directly. When you push down, it activates the front electric brake too. Smart!
The S2 Booster costs $999, which converts to about £800 or AU$1,300.