I've been thinking... if the Model S had sensors in all seats, then it would be able to track Wh/passenger-mile (in addition to standard Wh/mi). This, I think, would be a much more meaningful real-world statistic, and would make consumers much more vividly aware of the efficiency benefits of carpooling. For instance, driving solo, I typically average about 340 Wh/mi. Imagine if the dashboard were to display ~170Wh/p-mi when you're traveling with a passenger! (or 70Wh/p-mi, with four passengers!) For hypermilers, or anyone who cares about their driving efficiency and environmental impact, I think this could go a long way. It's sobering to think that hypermiling at 35MPH solo with the A/C off, is no better (in Wh/p-mi) than a double-occupancy car cruising 80MPH with the A/C blasting. By the same metric, a fully occupied Range Rover is just as fuel-efficient as a solo-driven Model S. Food for thought. With 34k miles on my Model S, my lifetime trip meter shows 352 Wh/mi. I'd guess that my average passenger-aware efficiency is around 250 Wh/p-mi. (In other words, average occupancy of about 1.3 people.) But this is entirely speculative. I'd be curious to know the actual number. Thoughts? Would you like it if Tesla did this? If you like, post your lifetime Wh/mi, and take a guess at your lifetime Wh/p-mi. It may be instructive.