OK guys, I did some modifications to help sort things out.
1. I sorted the sheet by kg/hp, and the then by time.
2. I added 2 columns: one for the projected time according to the regression formula, and another for the difference between the projected and actual times. This quantifies the divergence from the regression line.
3. I added a row for the E92 M3 with 8:02 time, and 2 rows for the GT-R with the 7:38 (one is for the base 480 hp version and the other for the speculated 530hp version by Motortrend). Since there is ambiguity associated with these runs, I did NOT include them in the regression analysis, so the regression line formula has not changed.
4. I redid the plot two show the speculated M3 and GT-R kg/hp vs. time datapoints.