I agree that, once a design or engineering decision is made, the cost is minimized. But the original decision to put the battery in the trunk wasn't based on cost because it's NOT cheaper than putting it in the engine bay. I also agree that there are many proper ways to put a battery in the passenger cabin. But they're all substantially more-expensive, more-complex, uglier, & less-safe than leaving it in the engine bay. And why would you want to take up passenger/cargo area with a battery? You don't need to access the battery while driving. And if you want to redistribute the weight, it's better to put that weight BELOW the floor than above it, which eliminates many of the problems mentioned so far. That's not an option in cars because there's no height between their floors & the road; either for the battery itself, or for access to inspect/maintain the battery. So theirs HAS to go above the floor if it's not in the engine bay. In a high-riding truck built on a full ladder frame...