Wel, let's say your in Florida...
Gas bike = Register as Moped.
Register = $$
30mph = ride on the road, not bicycle lane.
Gas now is $3.50 gal so for my .32c in electric, I get almost the same distance. (Plus, I can recharge for free, wherever there is an outside outlet. (Ex. Starbucks)
Now say you need to do that once a day.. The price is 10x's mine. After a year, that would be $1000 or so compared to my $100.
Now, do you really need to go 120miles AND STILL KEEP on going all day?
I can take maybe 50miles at one time and need a (buttocks) rest.
My recharge time may be at that point 1.5 hours, but no worries even after only a 50 mile ride, if I need too.
(Starbucks is awesome, free wi-fi, coffee, etc.. Did I mention free recharge?
)
Oh yeah, if you're using a two-stroke you need oil too.
There's about 500 more reasons I could go into where ultimately my price of bike outbeats a gas bike.