Performance/Mileage vs. Octane Rating

87 is recommended. Higher octane may cause error messages.

 

If the engine was created with 87 in mind, it makes no difference what octane you pick. Supposedly the computer realizes the differences (I haven't seen it though) and changes the spark accordingly. The savings is not realized with MPG at all though.

I have noticed differences on older cars (my '79 VW Bug for instance) with knocking and things. But with today's high electronic cars, (and motorcycles ... '99 Honda VFR800) the octane rating game is about as controverisal as the synthetic vs regular oil debate.

When I worked at CARB (California Air Resources Board) I asked the scientists about this and most of them agreed it was okay to put in the lower octane as long as the engine is designed to run with it.

I think the RX400H is going to be tuned to a higher compression therefore higher octane (or else it might knock) but the Hylander might be at a lower compression. However, given the joint press releases that put MPG and engine sizes on par together, I certainly HOPE that Toyota doesn't require a higher octane gas!

 

Here's what Tom & Ray and the FTC have to say about buying higher octane gasoline than is recommended by your owner's manual ...

http://www.cartalk.com/content/columns/Arc...October/11.html