tesla says bat life expectancy 8 years then warranty is overIn this example, one would already spend 30k annual on fuel.
2 years of that and your proposed solar cost of 50k would have been cheaper. (And don't worry, Tesla makes great battery packs)
Besides that, your proposed cost of 50k is a bit high considering 4kw of panels is $9016 ($2200 federal tax credit brings it to $6800) and a Powerwall is $9500 ($2200 federal tax credit brings it to $7300). 2 sets of panels for 8kw total and 2 Powerwalls would end up costing around 25k installed with the credits.
As far as an 80k car goes....
BRAND NEW Model 3 Long Range can be had for 45k FYI.
New battery for Model 3k costs ~7k and is up to the owner when they want to swap out.
Battery degrades ~10% over 160,000miles. So would hold 80% charge at 320,000 miles (Degraded 20%).
That 15,000 miles/year would take 20 years to reach 300,000 miles. SO double the proposed "10 years for new batterys"
Diesel Passat's were great cars.
So were Geo Metro's
and Toyota Tercel's
and Chevy Sprint's
and Honda Civics
Nowadays, cars have gotten bigger and safer, and more luxurious with more features and options. The closest thing to that now is a base model Honda Civic getting 30/38mpg for 21k which is arguably a good deal.
But will also need oil changes every 10k miles, engine maintenance, etc.
(30 oil changes over 300,000 miles! wow! 60 if you do it every 5k) How much is an oil change?
And you might need some spark plugs and air filters every now and then. And let's not hope you need to do the water pump or head gasket or radiator or spark plug wires or coils/distributor or fuel injectors or fuel pump or fuel filter or MAF sensor....