At least in the medium-term future we would at most be able to use is Hydrogen->Helium which would yield 6.45 x 10^14 Joules [1] which is equivalent to 179 GWh

At least in the medium-term future we would at most be able to use is Hydrogen->Helium which would yield 6.45 x 10^14 Joules [1] which is equivalent to 179 GWh which at 200Wh/km would be 8.95*10^8 km. That's still enough to go 20.000 times around the globe and longer than any car is known to have lasted so far[2] [1] https://www.phys.ksu.edu/personal/wysin/astro/review9/p4.html https://www.phys.ksu.edu/personal/wysin/astro/review9/p4.htm... [2] https://en.wikipedia.org/wiki/Car_longevity https://en.wikipedia.org/wiki/Car_longevity