I'd estimate a driving range with the electricity consumption of an average 4-person household (4000 kWh/year in Germany) of at least 20k km (@ 20 kWh/100 km).

I'd estimate a driving range with the electricity consumption of an average 4-person household (4000 kWh/year in Germany) of at least 20k km (@ 20 kWh/100 km). So that would roughly double the household use. Add another 4000 kwh for heating around 50-150 m² (90-25 kWh/m² per year for a modern home in Germany). In Germany you can use about 1.000 kWh/kWp per year from the sun, so one would need to install 60 m² of panels @ 20% efficiency for that. The main problem is storage for the winter - or where am I wrong?