I recently returned from a 13-day round trip from California to Milwaukee, Minneapolis and back. I thought this would be the perfect trial for the trip planning feature and the estimated battery reserve feature. I understand the trip planner is "beta," so I set the bar low for results. Here are my actual results and observations which I hope Tesla will give serious consideration to when they enhance and upgrade the trip planner: We set off for Kingman, Arizona the first day along SR99, SR58 and I40. The trip planner was pretty good (despite routing us to Harris Ranch--a needless 90-minute detour plus 15-minute charge) at estimating the stops at Mojave, Barstow and Needles. The total drive time to our destination included the time they suggested for charging. The drive was in relatively normal conditions, and the reserve estimate to reach each of the Superchargers was close enough so as not to be of concern. However, the display said that it was "safe to resume trip" with a 5% buffer calculated to our next charging stop. I was leery of such a thin margin, so we always had at least a 12% buffer for shorter legs and 20% for longer legs. The few minutes extra time taken for additional range in my opinion is cheap insurance against unforeseen circumstances. (More on this later.) I charged at Kingman to 82% in the evening before retiring. When we started our journey the next morning and set the trip calculator for Durango, Colorado, it directed us to return to the Kingman SC for a 5-minute charge in order to reach Flagstaff even though the trip estimate indicated a 15% reserve upon arrival. This detour feature was becoming annoying, so I canceled the trip planner feature for the remainder of the journey. We took a scenic route through southern Colorado, over Wolf Creek Pass and into Walsenburg before heading northeast on Colorado 10 and then due north to the SC at Limon. I highly recommend this scenic route off the SC highway as it was easy driving with stops in Pagosa Springs (70A) and Alamosa (40A) for two-one hour plug-ins. Interstate 70 across eastern Colorado and Kansas was a breeze; EVTripplanner nailed the usage within 4%. We decided to take highway 54 northeast from Columbia, Missouri and reach Springfield SC from the west via I72, and a 4-hour L2 charge was enough range to reach Springfield from Columbia easily. My return trip was supposed to be along I90 through South Dakota and then angling northwest through Broadus, Montana and charging at the RV park for several hours before reaching Billings. However, due to snow and temperatures in the 20s in Rapid City (and even as far south as Fort Collins) I decided to return via Interstate 70 through Worthington and Council Bluffs. Things got interesting driving west through Kansas the next day. I charged to 90% at Topeka to reach Salina, and made it driving 65 the entire way with 39%, averaging 340 wh/mile. I knew there was elevation gain from Salina to Limon, and it was getting breezy in the late morning, so I charged to 96% at Salina to reach Hays, 94 miles west. My expected buffer was 29%, so I felt confident! Wrong! Thirty miles into the trip the reserve had dropped to 18%, so I slowed down from 65 to 58, and I reached Hays with 5%. I then max charged at Hays to reach Goodland, 143 miles west. The estimator indicated a 32% reserve when I left. By now the wind was 30+ MPH from the west, so I figured I would start out at 60 MPH driving into the headwind. Again, the reserve dropped precipitously after 20 miles, so I kept lowering my speed down to 48 MPH for the last 80 miles. The reserve finally leveled out at 9% reserve with 60 miles to go, and I reached Goodland with 7%. These two legs took almost 420 wh/mile! I thought that I had factored enough buffer to account for both elevation gain and headwind, but I missed badly. I have concluded from my lone experience that the trip planning feature needs to expand its calculations by having some sort of input from the driver to account for spontaneous changes in weather or temperature. I presume the software knows the 1,500-foot elevation gain over the 143-mile drive from Hays to Goodland. The software needs to have the driver input options like estimated wind speed and ambient temperature in order to consider those factors on range. Once the calculation is determined, the driver should be notified as to the estimated wh/mile at different speeds--so the driver can make a reasonable determination to keep his speed early in the drive at 50 or 55 to have a reasonable buffer. The software might be able to notify us that our speed is good or whether to slow down from 55 to 50 or speed up from 55 to 58 as circumstances dictate. I can imagine new owners being totally naive about this complicated issue and wind up stranded and very upset that they ran out of juice 35 miles away from any charging spot, let alone their intended Supercharger. Needless to say, my crawling along Interstate 70 at 48 MPH for 60 miles was not a good public relations campaign for driving BEVs! One final observation about the navigation program: My last leg to return home was to get from Reno to the Manteca SC by taking US395 south to Minden, then taking SR88 over Carson Pass to Stockton and then onto Manteca. The program first routed me back to Truckee and then down Interstate 80. I tried again south of Carson City, and it routed me to US50 to South Shore and into Sacramento. At Minden, it routed me over Kingsbury Grade to South Shore and Sacramento, again on US50. At Woodfords, it routed me north on 89 to Meyers and US50 and into Sacramento. It wasn't until I had surmounted Carson Pass that it decided I really knew where I was going and kept me on SR88. We users should be able to select our route(s) among different choices presented instead of one pre-determined route that focuses solely on Superchargers. So, my suggestion to Tesla is that until Superchargers or convenient L3 charging/80A L2 opportunities are ubiquitous throughout the country where we are never more than 60 miles away, is that we need some sort of user input to guide us into how much to charge and at what speed to drive until we are in the clear.