r u talking about different cities or just in one big city?

no big deal. But I doubt if you can take the compensation from both company. Don't you need to hand in the receipt for gas? Then, you have to make up a lie to one of them expalining why you don't want to bother to get the gas fee back. Otherwise, you surely can and should take the compensation from both companies to save yourself some trouble.

我前面报mileage的时候对方都是要求给一个mapquest的driving direction，上面写了mileage。toll才要receipt，我还常常忘了要receipt

A到B和B到C都是上百mile.