gpsman:

The highlander has a really high compression engine ( like 10.8 to 1). It may well benefit from higher octane gas in a performance sense. Wether it will get better fuel mileage is left to be seen. As the owner of both an FEH and a HIHY, I can tell you that most of the driving skills cross over, but some do not, for instance, the low gear advantage doesn't help on the highlander because the "B" position, analagous to the "L" position in the Escape, uses enging braking. To the HIHY's credit, it is MUCH easier to get the ICE to drop out while driving the car; no double tap, just lift your foot a tad while coasting and it goes.

MM

Hi

We live in Florida where its fairly flat. We go on trips to Orlando and back that logs about 140 miles. If we use cruise @ 63mph, we can get a fairly steady reading of 33mpg.

cheers

A blanket statement like this may be inaccurate because it depends very much on the design parameters of the engine and the the programming of the engine control computer (ECU).

Many vehicles these days are designed to run optimally on higher octane fuel (91 or higher). These same vehicles will run perfectly well on 87 octane fuel. Current state of the art ECU's used in today's vehicles can compensate and adjust for an extremely wide range of fuel and atmospheric conditions.

Additionally, your FEH uses a 4 cylinder Atkinson cycle engine, designed for high efficiency/high fuel economy and extremely low emissions (at the expense of power). The Highlander Hybrid uses a standard Otto cycle V6 that was designed to use both high and low octane fuels, and is tuned for power and low emissions. As others have noted, the HiHy V6 has a very high compression ratio, which is a sure sign that it was designed with high octane fuel in mind.

So your experience with the FEH does not necessarily translate to what someone would experience with a Highlander Hybrid.

I've been running 92 octane premium in my HiHy for over 4200 Miles. I'm currently averaging 29.5 mpg. At 5000 miles I'm going to switch to 87 octane regular for the next 5000 miles. Then I'll have some concrete data for comparison purposes.

Okay, my bad. I guess the HiHy and FEH are more dis-similar than similar.
I guess they are only similar in how they look from the outside.
I still 'think' you will waste money on higher octane fuel.
This is an SUV/ Wagon type vehicle, and how often do you have the pedal to the metal and wide open throttle? If almost never, then you don't need high octane.
If almost all the time, then you use way too much fuel in the first place!

I'm confused why people who are interested in "power" buy hybrids.
I can drive a 4000 pound vehilce ( my FEH ) all day with 15 horsepower.
( and get over 60 MPG to boot! )

Any vehicle choice involves some level of compromise. In my situation I needed a 4wd vehicle that had seating for 5+, could tow 2500-3000 pounds, and had low emissions and good gas mileage. The HiHy fit the bill nicely. I could not find another vehicle that did. I only own one vehicle so it had to meet all of my needs. The HiHy is not the best at any single task, but it does well at so many of them that it is an excellent all around vehicle for a one vehicle household like mine.

I may very well be wasting money on high octane fuel, and I'll know more as I make the switch to 87 in the next month or so. However, I'm getting much better mileage with my HiHy than most are so I'm real curious as to what will happen when I start using 87 octane fuel.

However, I'm wondering about the timing of switching around November 1. The weather will be getting decidedly winter like and if my FE falls off I won't know how much (if any) of the decrease will be because of the octane change and how much is because of the weather. Because of that, I may delay the switch over until next spring at about the 7500 mile point.

So, John, the operative word in my message was "test." So far (3 tanks) the average MPG is up to 30.1, with mostly interstate/highway driving over 55mph. I am pleased.

BTW, the manual suggests Octane Rating over 87, or 91 or higher for better performance. (page 302.)

I guess you already got the answer on engine compression. Maybe you better stick to your own vechicle when answering!

EMO

On my camry hybrid there is a point where the electric motor stops driving the car and the ICE starts (40mph) After reading some posts about this I tryed It and got a huge increase in mpg. I have not tryed any 40 mph or slower speeds on my hihy.Has anyone found a high mpg sweet spot with there highlander...JOE