It doesnt take long to hit 80,000 mi.es. hell just in regular use and a 60 mile one way commute one day a week has put 10k miles on my jl in 7 months. So my warranty would be done in about 56 months or basically 4.67 years.Federal emission law requires an 8 yr 80,000 mile warranty on the generator and 48v power pack so that is what is listed in the 2019 Jeep warranty manual. I wouldn't buy it because it is far too complicated and requires premium gas which, cost-wise, does away with the small increase in mileage improvement. Also, the extra battery causes more pollution because battery manufacturing is one of the most toxic processes.
And as to the carbon footprint reduction with a plug-in electric Forbes a few years ago printed a study that was done that said just about everywhere except the NW it was breakeven or worse for the electric vehicle because most states rely on carbon fuel to generate electricity. Also don't like everyone paying taxes to incentivize people to buy electric cars (or solar panels, etc.). If a technology that has been around for decades can't sustain itself without my tax dollar it doesn't need to exist.
And right now the cost of battery replacement is very expensive so any car with batteries looses value because the next buyer knows it may cost a lot to replace them while they own the car. Yes we need to find a way to have vehicles that can go 500 miles with instant replenishing of fuel with reasonable cost but we aren't there anytime in the near future. America is a big country and while some only travel a few miles a day and can wait for an overnight charge, many live in areas where they need to drive long distances everyday or have jobs that require long trips. Plus do you have a car for short distances and one that can drive further for holiday and vacation travel? I don't want to be 4 wheeling in back country when my electric Jeep runs out of power. Not the same as bringing a couple of gallons of gas to get going again.
And I am not a millenial but I was a mechanical engineer that did design solar systems so I'm not against alternate energy but it has to make sense.
Plus that battery warrenty isnt likely to transfer to a new owner. Or god forbid you mod your jeep and they dont warranty your battery.