It would be interesting to post smog emission results for our E39s (for comparison)
It would be interesting to post state smog emission test results for our E39s (for comparison among us).
Who know what we'll learn from this ... I'll start.
Below are my emissions test results (long story here) on my 2002 E39.
What I learned is that it makes NO difference (for emissions tests) whether you use 87AKI or 91AKI California-specific fuel (actually, the 91AKI results are slightly worse but not statistically so).