part of the car service/cab problem is that ISP is in NY and you want to end up in NJ. Thats an OT (Out of Town) when I sat on the seat it meant almost 2X on the fare. Since its orginating in Suffolk county going thru Nassau County and then NewYorkCity and ending in NJ, it just might be cheaper to buy the tkt to EWR at what ever price. Of cause thats to be divided by 2 or 3 but still since they'll have to repeat it on the way back and the flight is on WN after all, if I was gonna be flying Id pass on it and pay the little extra and fly into EWR.
I use to get a few regulars from Wall St that had me drop them on the Queens(NYC)-Nassau County border. They either got picked up there, parked their car there or in 1 case lived 3 blocks over the border. Reason most firms werent willing to give the free rides to their employees if it meant going beyond the city Why? it cost alot more, the fare would be bet 50-100% more for less than a mile. It wasnt by mileage but by Zone when you left the city so the 50-100% mark-up was worked into the Zone fare.
so even if you have a 10 mile drive from Manhattan to NJ the fare was close to $40 plus the tolls, that was back in '85. doing $2 a mile x 10 is worthless. Also keep in mind that you might get a good deal from ISP but not find it any where near that from Jersy City back