The Aptera Forum
I think their website's www.aptera.us solar atlas to calculate the MAX solar generation for your region might be you best indicator:
And that would be for a model with full solar
My experience with a grid-tied system at least an order of magnitude larger than what you could put on an Aptera says some days I get better than 50 kwhrs. Some days it's near 0. Same goes with the car. An optimum day will get the max possible for sun exposure, some days it will be negligible.