My 01 RX-300 gets better MPG with 93 octane but feels lethargic. I never thought this would happen.
87 octane feels much more responsive and the MPG is only a little less. In other words, the MPG of 93 octane just about offsets the cost differenct. I use cruise control just about all of the time so, Im creating my own controlled environment. Never fails, 93 get better MPG(about 7%-8%). Cost difference, about 7%-8%.
So, I did an experiement. There is a straight flat stretch of farm road near our housing developement. Nothing around but a cow or two. I use this road for timing my cars(0-60 only). I have a very expensive Fisher Scientific Stop Watch(easy to start/stop and reset) that I use along with just stomping on the gas. I run the vehicle in both directitons several times. Im consistant with myself in the way I do this. Not trying to get faster times, just trying to see if there is any difference in my seat of the pants feel between octanes. This isn't Car&Driver but it still shows consistancys or lack of. My results are:
87 octane-0-60...8.6 sec. +/- .02 sec. aprox. 18mpg city/22 highway. Often a bit lower on both city/hiwy.
93 octane-0-60...9.4 sec. +/- .02 sec. aprox. 19.5 city/24 highway. Often a bit high on both cith/hiwy.
I have used/tried other octanes such as 89 and 91 but have not tested them in 0-60 only MPG. 87,89, & 91 octant all get about the same MPG with a couple of tenths of one another. I've tried them for several tankfulls. The 93 octane is where the difference comes in. Better MPG but the most lazy feeling. Not terrable, just noticable in the seat of the pants feeling. This is fine when we're just tooling/cruising around or on a long freeway trip at a set speed, 60, 65, 70 mph with the CC on. Good MPG while on a leasurely drive.
