This depends on their storage. The ideal storage conditions are room temperature out of direct sunlight. Do not place near extreme heat or light. Extreme heat may cause a fragrance to oxidize or change its odor. When stored properly a perfume will last almost indefinitely.
Heat builds quickly inside a vehicle.
Liquids expand and contract with temperature changes. Excessive heat may cause the bottles to break. No, the ideal storage condition for perfume is room temperature. This depends on your personal preference. Spraying gives a more even distribution.