This is from a site dedicated to using "rocket" fuel for automobiles.

-Toulene
-R+M/2...114
-Cost...$4.50/gal
-Mixtures with 92 Octane Premium
-10%...94.2 Octane
-20%...96.4 Octane
-30%...98.6 Octane
-Notes: Common ingredient in Octane Boosters in a can. 12-16 ounces will only raise octane 2-3 *points*, i.e. from 92 to 92.3. Often costs $3-5 for 12-16 ounces, when it can be purchased for less than $5/gal at chemical supply houses or paint stores.

As you can see, it takes GALLONS of hi-octane toulene (114) to appreciably increase the overall octane of the gas in your tank.

On my list of things to try.

glenmore
1991 300CE
1990 LS400