137 km would mean it was doing 3.7 km per kWh. I think in miles (and miles/KWH-sorry we tend to work it the other way round in the UK) and that would be about 2.3 miles/KWh. That's a long way from anything I've every got near freezing. My worst economy on a very hilly route at about 70 MPH (112 KMPH) is 3.2 miles/KWh. This is a useful website and generally seen as pretty accurate:
https://ev-database.uk/car/1285/Fiat-500e-Hatchback-42-kWh. That suggests 100 miles (160 km) at -10 degrees.
The way you drive an EV is far more important than in an ICE car. On my main commute at this time of year, I get about 4.8 or 5 miles/KWh. My wife, who doesn't often drive the car, did exactly the same journey at the same speed and got 3.5. It's not about driving slowly but smoothly. I use the "Normal" mode because I don't particularly like one pedal driving, but particularly on motorways with constant speeds the "Range" mode or the cruise control will improve things too as the car will smooth things out automatically with maximum regen etc.
I reckon that 160 km figure is pretty accurate if you drive reasonably carefully.