Well, I am going to say, NO! When they're in the engine compartment, they are right in the way of cooling air coming into the engine bay. As were the batteries that are located in the trunk or backseat area, or even the wheel well of the car(Chrysler), don't seem to show any benefits for longevity. I think the battery placement is for weight balance.
Batteries that are in vehicles living in the HEAT BELT suffer from more earlier failures regardless of their location in the vehicle. Batteries not maintained also fail early regardless of the location in the vehicle.
This is just my opinion.
CB