Well firstly it depends on the bike.
Secondly it doesn’t matter if you get paid to drive it or comes out of your pocket, the math is the same. Car will still be on the road and require it’s own insurance and reg etc, so bike is extra fee in every single way other than better mpg. Figure out how much you spend a year on gas (Average person is around $1500-$2000, you’re presumably more), divide that by 4 and you will get your early savings just to gas. At $500 a year it will take quite some time to make the initial “investment” back.
Just saying.