[s-cars] Lowest octane for road trip?

[tim rad]

At risk of incurring the wrath of the Audi Gods, my 92 S4 drinks
regular 87 octane quite regularly.  I can't tell the difference
between premium and regular.  Must be my knock sensor is working well.
(over 20,000 miles with 87 octane...)

If you recall, Car & Driver did a similar test with a BMW M3 and the
0-60 times were so insignificantly different that the average Joe
wouldn't even have noticed.

I figure that at least if I use regular, I will get fresh regular,
where if I buy premium, it might have been sitting in the tank for
quite some time.

Tim