Been thinking about how EV trucks seem to get more range than cars/SUVs. Is this because of the surface area of the vehicle compared to the weight (with an empty truck bed)? Would an unloaded EV El Camino theoretically get better “mileage” than something like a Bolt?
First and foremost it is the mass that defines the range of an EV, closely followed by the aero drag efficiency. Rolling resistance and transmission losses are pretty minor. A mindful driver who doesn't race up to red lights and doesn't mind getting hot on a hot day and cold on a cold day will increase the range by reducing HVAC load. The type of terrain and ambient temperature are factors. I would be surprised if something as inefficient as a truck gets anywhere close to a sedan.
AFAIK EV pickups lag in efficiency but make up for it in sheer battery pack size. The F-150 Lightning gets 2 miles/kWh (cruising I believe) while a Bolt is probably around 3-4 so be sure to double-check the range compared to the usable capacity ratings on their batteries!
You're confusing mileage and range. Range is a function of the vehicle's energy capacity, whether it be fuel or electricity, whereas mileage relates the energy expended by the vehicle to travel a certain distance.
It might be correct to say an F150 has better range than a Corolla (which might not even be true), just because the F150 has a much larger fuel tank. But, as is obvious, the fuel an F150 expends to travel a certain distance is much larger than that expended by the Corolla, or you'd say the Corolla gets better mileage than the F150.
It's the same in EVs. Simply, an F150 Lightning has a higher capacity battery (fuel tank) than a Bolt, but the 'mileage' of the Lightning is much worse than the Bolt.