I respectfully disagree. The SOC range is very accurate, and there's an easy way to calculate it, you don't need to do a "test trip". Just take the current rated miles SOC, and divide that by the % battery SOC, and you get the estimated 100% charge in rated miles. In my P85DL, this is remarkable accurate +/- 1 mile. No matter what state of charge I am at, the calculation for me is always between 266 and 267 rated miles. And when I do a full 100% range charge, that's what I get. And if I drive at approximately 300 Wh/mile, I'll pretty much get that same rated mileage out of the battery (I think for the P85D the calculated rated consumption rate is 290Wh/m). But my average consumption rate is more like 330Wh/m, so I get about 10% less than the rated range on the battery indicator. Likewise, if you drive more conservatively at less than average 300Wh/m, you'll get a lot more than the stated rated range. It's not that complicated -- it's all about watching your Wh/m during any trip and adjusting your mental calculation accordingly, since Wh/m changes due to many different, changing, factors.