If the car is advertised as certified at a certain price then the extended warranty is included in the price. I’ve never been charged extra. If you buy a low mile used car, the certified warranty is often better than the new car warranty. The fees other than taxes are always negotiable. Nitrogen in the tires instead of air only matters if you live in a climate with wide temperature swings between day and night or one day to the next. The tire pressure warning lights will drive you batty. Nitrogen is more stable so that doesn’t happen. I hate the green caps myself, so I’ve never gotten it before.
Exactly. Plus you can still put air in a nitrogen tire if that is all that is around and you need it.