[edaemon]

The cost comparison should be more than just the thing that provides backup electrical power, though. The Lightning includes a vehicle and a different power source. It's an entirely different system.

Generac + truck + propane + gasoline

vs.

Truck + electricity

Over time it almost certainly works out in favor of the Lightning. Throw solar panels in as a source of power (for both your house and vehicle) and it becomes even more cost-effective.

[bluGill]

Sure, but I have propane for heating anyway. My generator is already pretty old and should last a lot longer, meanwhile cars rust and wear out after about 10 years.

[lupire]

With maintenance, cars last about 20years unless they get extremely high mileage.

[lupire]

Truck also has insurance cost, and coat (energy, higher insurance) of using an overlarge truck for driving when you would have used a smaller car one otherwise.