dylan400h

Less air, but a throttle plate is not an airtight valve. When it is "closed" the air necessary for idle still flows.

As far as I know, there is no catalyst temperature sensor, just the upstream and downstream O2 sensors. Once a cat has lit off at about 250 degC, its temp rises rapidly from the fuel reactions to its operating temp. When the engine stops, so does the airflow, so the ceramic catalyst in its ceramic matt packaging, stays hot. I dont think they do anything other than initial cat warmup for a cold start. It does beg the question what happens when the engine spins with no fuel, either in B mode, or warp stealth with electric only above 43mph, does cold air cool the cat? Warm catalysts are all about good performance on the EPA test. Emissions control systems got so effective that all of the emissions in the test came from the cold start period before the catalyst lit off. 0% effectiveness for 30 seconds or a minute overdhadows 99% versus 99.5% effectiveness for the rest of the test. So especially for SULEV, startup emissions are critical.

Everyone who has been stuck in traffic for any length of time, me included, has achieved low 30's MPG for sustained periods. Remember what the EPA test cycle is, a time and speed profile that any car, no matter how underpowered, can easily follow with very gentle starts and stops. I think another factor in the 400h city MPG is that the 400h has about the same size battery as the Prius, which puts it at a disadvantage in stored energy utilization. In my experience both the Prius and the 400h benefit from special, high MPG driving techniques. I get in the high 50's in a Prius when I drive very carefully, versus high 40's normal.

The engine runs for an auto charging session if the battery gets down to 2 bars (magenta). That is lower than the Prius is allowed to go, so Toyota is getting more aggressive in battery utilization. When you start up there is an engine warm up to get the engine, but especially the catalytic converter heated up. I don't think the 400h has a heat battery coolant cannister like the Prius. In this case you may not see the motor on the display since it may or may not be charging the batteries. I have seen the motor running but not on the display. They run the engine at slightly elevated RPM with a very retarded spark timing to get the exhaust as hot as possible with no load to heat up the catalyst even if the battery does not need charging to its 4 or 5 bar target level.

Yes, I agree completely. The cars seems to use the engine more smoothly under cruise. I believe it has other programming to improve efficiency as well. I carefully observed what I think is an interesting algorithm at work. With the cruise on, the car holds speed pretty accurately, but when you crest a hill and the engine turns off to coast, the cruise allows the speed to coast down 5mph before restarting the engine and accelerating back to the set speed. Furthermore, while it is coasting down, it runs the electric motor only (warp stealth) to try to maintain speed as long as possible before restarting the engine. To observe this, set the cruise high, 75 or so, and set the speedometer display to the energy use graphicto see speed and energy together at a glance. The system is smart. I had assumed that I could do better than any cruise system by anticipating hills and blending the speed, but this is not just a dumb setpoint only cruise control. I have taken to driving with cruise as much as possible, using the stalk to accelerate and coast within reason in light traffic. I really think this car should have a sport button that give you the engine always available for quick acceleration, and an economy button with much less aggressive software. One of the major benefits of all these computers is that it should be able to be two different cars at whim of the driver.

My NY dealer said they wont get their first one until Friday, what gives?

I remember that some Prius owners figured out a hardware hack where you connect a switch in line with the speed input to the nav. Turn off the switch, and the nav thinks you have stopped. That doesn't work any more? Those Prius folks are pretty crafty, I hope they get it. I know that they are working on the phone as well.

Try here:http://www.l-tunedparts.com/product/?id=736 $299.00 plus shipping. Don't know anything about this vendor. The grill is a Harrier grill with the cool emblem! This is the one that I'd like to see a group buy on! It's really very cool! ← I love the look, and I want one, but when I look closely at the picture, it looks like a different hood. Do you see the raised element between the grill and the headlight? The US RX doesn't have that. It might be the same grill anyway. I like the Harrier emblem.

The prius has a compression ratio of only 9.5:1, less than the 400h. 13:1 is the expansion ratio, though I guess you are right to call it the base compression ratio. As you know, the efficiency comes from the high expansion ratio without a high compression ratio that could cause detonation. I looked at the Toyota Japan website, and found that the Prius already uses early intake valve closing to achieve the Atkinson cycle. I thought that they used linkages. So why didn't they just put in different pistons and change the valve timing to Atkinson cycle? Perhaps they have to some extent, 9.5:1 compression 10.6:1 expansion, and that resulted in the reduced power. It does seem like a missed opportunity.

I have looked for information on the engine cycle for the 400h, but found nothing other than references to "changes in the variable valve timing". Some of the increased expansion of the Atkinson cycle can be achieved with early intake valve closure, but not all. Prius, as you said, and Ford Escape use Atkinson cycle. Disappointing I agree, but not a deal killer for me. The combined mileage for a vehicle of that size and performance is still excellent. What would Atkinson buy you, maybe 5-10% better highway mileage, 31.5-33 vs 30? Dylan

Here is a Lexus preliminary feature list for the 400h: http://pressroom.toyota.com/presstxt/2006l...06lex400h_s.pdf As for price, the way I look at it is that to upgrade from a 232hp V-6 Mercedes ML350 to a 288hp V-8 ML500, it costs $8,450 (MSRP $38,670 vs. $47,120). For that price premium, you get better performance, more features, and WORSE mileage! The ML350 has almost the same base MSRP as the RX330, and the power improvement is comparable that of the 400h over 330. I fully expect to pay a healthy premium, perhaps even that much. Dylan