Increase MPG avg. 2.9
 

i did a MPG octane compar-o, over 3,000 miles. as per 87 vs 89 vs 91-94 octane. i averaged 2.9 more mpg using regular automotive grade fuel with the highest AKI rating vs the lowest.

Its very dependent on the vehicle. Vehicles with specially tuned, high compression engines (motorcycles, sportscars) will do better on high octane. Most others will get better mileage on low octane. The only other factor to consider is that in some areas the premium fuel is ethanol free, and the regular octane is an ethanol blend.

Not 100% sure with bikes, but with most vehicles, filling up with a higher octane than your vehicle's tune asks for is just wasting money.

I believe most, if not all motorcycles require premium fuel.

i use the highest AKI rated fuel and a ethanol treatment. the ethanol treatment helps a little on the avg. mpg. by 1.5 mpg.

My 2007 Ninja 650r (twin) has an 87 octane minimum recommendation.

Sportsters called for 87...until they put EFI on em. 91+ is req'd now. Blah.

to many different grades you have there.
we have 95 and 99 and some sell 98

Octane stuff is kind of cool. This is the best article I found that describes what Octane does:
Octane Ratings

So octane needs depend on the compression of the engine. It looks like your bike has a fairly high Compression Ratio of 11.3:1
Total Motorcycle Website - 2005 Suzuki DL1000 V-Strom 1000

This would suggest that even though your bike has proven to run on lower Octane, as you pointed out, you will indeed see better performance with higher octane because your engine design (compression) is high enough to take advantage of a higher octane.

One thing to consider is the performance increase vs the cost increase. If the fuel economy increase is 5% but the cost of higher octane is 8% then maybe it's not as economical (of course better fuel economy is kinder to the planet and higher octane might perform better).

My 06 Super Glide requires premium.