Fabulous data, great work by Tony and a bunch of other testers. I did my own range test (not standardized), but I do have comparison data from 7 months earlier
Start (Full Charge) - 255 Gids
Work (20.2 miles) - 195 Gids
Home (40.0 miles) - 152 Gids
Work (60.2 miles) - 81 Gids
Lunch trip (69.6 miles) - 69 Gids (increased to 75 Gids when car turned on 6 hours later)
Part way home (73.0 miles) - 64 Gids (22.7% - got 82 miles previously from full charge to 22.7% Gids)
Part way home (82.0 miles) - 49 Gids (LBW, 17.4% Gids)
Home ( 89.3 miles) - 44 Gids (15.6% Gids; long downhill descent to get home uses only 5 Gids for 7 miles)
Temperatures were a bit warmer for this test (70 degrees and 5 Temp bars to start, high at work around 90 degrees F.), driving conditions were quite similar, perhaps a bit more stop and go on the freeway than usual which may have hurt my range a bit.
Range to 64 Gids - 73 miles
Range to 64 Gids 7 months ago - 82 miles
Calculated range loss to 64 Gids compared to 7 months ago - 11%
Difference in percent Gids remaining at 82 miles: 22.7% - 17.4% = 5%
Predicted range from this data (if gids are linear and car stops at 4 gids): (90.7% - 4/281%) * 89.2 miles/(90.7%-15.6%) =
(90.7-1.4) * 89.2/75 = 89.3 percent * 1.189 miles/percent = 106.2 miles (granted, not bad since there is a 1450 foot elevation gain and loss during the round trip)
Before anyone jumps up and down about different temperatures, etc., I will be repeating the test in a few months when it is cooler to see if there is any difference. While the range loss to 64 Gids appears significant, the predicted range to turtle is almost exactly the same as that done 7 months ago.
1) Without driving all the way to turtle it isn't possible to estimate the actual range, my extrapolation is only a guess.
2) It appears that Gids are highly unreliable as a predictor of how much range is left. The range doesn't appear to have changed much, but the Gids certainly have!