Due out this year, the Citroën ë-C3 specs are as follows:
44 kWh battery
NO heat exchanger
WLTP range 199 miles
Is it realistic to expect this car to drive 135 miles in winter conditions at 70 mph (M4, M3, A303 London to Somerset)?
I do a regular 160 mile Derby <-> Winchester non-stop trip in my Ioniq 38.3 kWh usable EV. 2/3 is duals, 1/3 m'way.
WLTP for your car is 199 miles. ev-database reckons the e-C3 has 44 kWh usable, 45 total.
WLTP for mine is 193 miles. ev-database says I have 38.3 usable, 40.4 total.
These 2 cars sound similar. Chances I have better aerodynamics, as the battery isn't located under anyone's feet, but in the boot & partly under the front seats.
I do this in winter at 10C temps at lorry + a couple of mph speeds, generally waiting until a suitable gap on the duals before I overtake. Motorways I can do steadily. I reckon on arriving with about 20 miles remaining, so around 180 mile maximum, always wise to leave a reserve in case of detours etc.
But I have a heatpump. Selecting Heating at the start reduces my range by 8 miles, and this is accurate, and my heating runs around 600W for 3 hours, so appx 1.8 kWh gone on heat = appx 4.5% my battery = 8 miles appx.
Without heatpump I'd perhaps lose 3x this, so around 5.5 kWh gone. So for you that would leave 38.5 kWh. You're going to lose more like 25 miles range I reckon.
I'm managing 4.5 m/kWh driving like this. Your battery is 1.15x larger but assuming similar range, I estimate you'ld get 4.5/1.15 m/kWh = 3.9 m/kWh. With 38.5 kWh available, gives predicted range 3.9 x 38.5 = 150 miles.
So you should be able to do your 135 mile trip with 15 miles in hand, heating on, in 10C temps, driving just-faster than lorries.
Can't see you managing it at 70 though. Aerodynamic losses go up as square of speed, so you may find the trip ends up longer if you drive faster, but then have to take time out to do a top-up.
Prevailing wind tends to be from the West, so chances are this will hit you on trip leaving London. A 10 mph headwind means your 60 mph cruising speed hits you like a 70 mph speed in calm weather, so you'll have very little margin. Best advice is start out slowish, say 60, and see how your remaining SOC goes. GOM in Stellantis cars is reckoned poor, so don't trust it if you are pushing the limits!