Mileage / Battery Use On 400h

[SW03ES]

If its anything like the Prius it takes some time before you start getting the good mileage numbers. Our mileage increased a lot on the Prius after 2500 miles or so.

You also have to know how to drive it, no quick starts or stop, nice steady acceleration and braking.

[scoobie]

Hey folks, you shouldn't adjust your driving style to fit the car, who's driving who here ? Just drive the way you normally drive and enjoy whatever extra the technology gives you, for some people it may be the "neck snapping" torque, while for some it may be that little extra mpg, and still for others it may just satisfy their urge to have the latest and greatest.

[RX400hGirl]

Hey folks, you shouldn't adjust your driving style to fit the car, who's driving who here ? Just drive the way you normally drive and enjoy whatever extra the technology gives you, for some people it may be the "neck snapping" torque, while for some it may be that little extra mpg, and still for others it may just satisfy their urge to have the latest and greatest.

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Drove home tonight from work, and got 36.3 MPG!! Wahoo! I'm in love with this car :D

[bikeandsail]

One of the primary engineering concerns that Toyota faced with this car was to insure the traction battery lasts at least 100,000 miles. They only use the midlle 1/3 or mayber 40% of battery capacity to not stress the battery.

I for one want my battery to last well past 100,000 miles and will not be doing anything to shorten its life.

Ron

So it looks like by measuring at the pump and not via the onboard gauges, the mileage may be close to what Lexus claims.  Lexus should fix the gauges if possible.

Here is the part that makes NO sense to me.

Why disengage the battery on a dead stop start when there is sufficient charge left in the battery?  If the battery is almost drained, then fine, engage the engine on acceleration.  If not, let the battery do most of the work unless I punch it.

To not engage the gas engine on a standing start takes a great deal of patience and is guaranteed to get horns blaring at you from behind.  A normal acceleration in city traffic almost always kicks in the gas engine.

It strikes me that Lexus should make a software update available that lets one put the car in performance mode or mileage mode.  Since I really have few occasions to use the 0-60 time, I'd rather have it in mileage mode.

I toyed with calling it economy mode (instead of mileage mode), but given the check I just had to write, I thought it a bit innappropriate. B)

Overall a great car!  I'm just venting a bit on this mileage/battery thing.

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[motion]

sad.gif I've been driving the 400h for a little over a week, but put about 200 miles on it. I can't seem to get anything over 19.7 mpg average . I've tried adjusting my driving style and this didn't help. I drive mostly in Los Angeles streets - lots of lights and stopsigns, lots of slowdowns. I've had a few clear freeway trips too. Is there any way of checking to know if your particular car's hybrid system is working correctly or "tuned" or whatever? Or perhaps as someone said, the computer may be giving me a lower MPG score then I'll find at the pump.

I have reached a charged battery (the bars on the battery symbol turned all green for a short time). Some mitigating factors could be that it's been warm so I have been driving with a little a/c on, but not all the time.

I know that it's a little early for me to be getting concerned but I see that others are doing much better with their new cars.

BTW I think the idea of creating a "Performance mode" and a "Mileage Mode" is a great idea.

Other than the underperforming mileage, I'm loving the Rx 400h! smile.gif

[1990LS400]

There have been several articles in the news about how Toyota and other manufacturers have asked the E.P.A. for permission advertise more realistic (i.e. lower) fuel usage figures for hybrids. I am not aware of the E.P.A. making any of these suggested changes. Manufacturers are not allowed to advertise mileage figures different than the E.P.A. figures even if they want to do so.

[patt]

motion, Have you reset the average mileage during that time or is it still running on the accumulation from mile 0? When we got our car, there was a pretty low average mileage (13 or 14 I think) from whatever the mechanic had done during prep and check-out of the car. If that is still in there, it will drag down the average. Things looked better once I reset that.

[LexKid630]

Do you think the hybrid batteries will be made different to last longer in the future models?

[patt]

LexKid, It seems probable that the batteries are big enough to do what they need to do and making them bigger wouldn't improve mileage. All the power is made by the engine. The most efficient use of the power is when the engine can run in its most efficient band and deliver the power directly to the wheels.

You always lose energy when you move power around - that is why you can't have a perpetual motion machine. In the case of the hybrid system, you lose energy due to resistance of wires and any inefficiency in the motor generator for instance.

Then why do the batteries help mileage? Here are some ways:

They provide a place to store regenerated energy from the braking - in a non-hybrid, the energy of your motion all is turned into heat from the friction of the brakes and is lost to you. In the hybrid, much of it gets turned into electric energy and stored in the batteries.

They allow the engine to operate in its efficient range - The gas engine never has to operate at slow RPM to start the car moving or to coast the car or at very high RPM for passing and other high speed acceleration. Depending on battery charge level, it is either off or it is on at a higher speed with the extra energy being used to charge the battery. Since the operating range of the engine is narrower, the designers can even make changes to optimize performance in this range over the performance of the standard engine that has to support a wider operating range efficiently.

Once the batteries have enough capacity to store the energy generated by braking under normal operation, to provide for acceleration and to allow the engine on/off cycles to be long enough for efficiency, there shouldn't be any gain in making them bigger. There would be a loss of effeciency due to needing to carry the extra weight.

[LexKid630]

That's VERY good engineering ;)

[SW03ES]

Let it get some miles on it and see.