RX400h

http://www.tirerack.com/tires/tires.jsp?ti...inSpeedRating=S

And I restate - BEST bang-for-the-buck when it comes to high-end tires in the OEM size.

Bang-for-the-buck, it is tough to beat the Bridgestone Alenzas. I paid $600 for all four and with 7000 miles on them, they still look brand-new. Whether they wear as well as your Michelins remains to be seen, but for now, I highly recommend the Bridgestones.

Just two months after we bought our 2006 RX400h (June of 2005), some guy in a pickup backed into the front corner of our vehicle at a gas station. It took one month before the body shop was able to receive the front bumper from Japan.

Rule of thumb: Don't get into an accident with a vehicle that is of a new body design. I'm fairly certain that should the damage have occured to our side door, an RX330 replacement would have been delivered, quickly. Unfortunately, the front bumper is an RX400h only part and we were somewhat upset as well.

Hopefully, you will be up and running, soon.

Dave

Well, as I mentioned before, a Prius driver tried to race (and beat) me, a couple of weeks ago. I agree that not all Prius drivers are out to achieve 60 MPG.

Dave

Tom,

Seeing that you live in Arizona, I'd say you are doing the right thing. The ambient temperature makes a big difference when it comes to the likelyhood of predetonation.

Dave

RX,

Your analysis of Lexus’s fuel octane recommendations in the O&M manual are not correct. Lexus says regular - 87 pump octane is acceptable and 91 pump octane is recommended. In the US pump octane is an average of ROM and MON. IE 87 pump octane = (91 ROM + 83 MON ) /2.

The proof is using the fuel. There is no knocking or reduced power as a result of using 87 octane.

Ron

Ron,

It is actually a bit ambiguous. The manual does not state that "pump" ratings are to be used, although this can easily be inferred by the nomenclature. The manual states "Octane rating of 87", but never mentions "MON" as an averaging factor. 87 pump octane does seem to work adequately during cooler ambient temperatures, but I would shy away from using it during the Summer months.

Dave

Dave,

The 91 RON in parrenthis implicitly indicates that the 87 is pump octane. IE pump octane 87=91 RON - approximatley. There is no ambiguity to me. I know what knocking is and in 60,000 miles, maybe 10,000 towing a boat t u[ tp 80 mph I have never heard a knock or had a loss of power.

All my testing on premium has indicated no better and possible worse gas mileage contary to Lexus claims.

Ron

Ron,

I'm fairly certain that the Lexus ECU acts similarly to that in my Corvette: When intake air temps exceed a certain threshold or pinging is heard by knock sensors, the ECU retards timing to prevent (further) predetonation. With over 200 HP, you may not feel a 10 HP loss under most driving conditions, but I guarantee you that if you were to instrument your car to measure acceleration times, you'd see an increase in time to accelerate to 60 MPH or more if using regular fuel vs midgrade or premium.

Granted, this difference may not be worth the cost increase to most of us, but that doesn't mean that there is no difference at all.

Dave

Surprisingly, many of the reviewers at C&D are well-educated. I believe Pat Bedard has a bachelors degree in mechanical engineering and others are quite perceptive at figuring out the whys and why nots of performance. I've also read elsewhere that performance will suffer as the battery reaches its low-point (about 60% charge?). For C&D, with their very accurate instrumentation, proving the concept is not very difficult.

Yes, according to C&D, the previous best 0-60 MPH time for the RX400h was 6.9 seconds. After fully charging its battery, they achieved a 6.7 second 0-60, which is better than that of a Porsche Cayenne-S.

Ha, that image is not very clear! I just went a trip to Beverly Hills, yesterday and the HOV lanes were humming along at 80 MPH. It is true that many Prius owners are timid drivers, but I ran up against one last week who figured he'd easily blast ahead of the RX400h to get into my lane. Little did he realize that the RX400h can do 0-60 in 6.7 seconds with a fully-charged battery! Needless-to-say, he saw nothing but my tail lights! :chairshot:

I don't take my RX in for "scheduled maintenance "services", since many of the items on the list are "check this" or "check that" type of things. Instead, I scrutinize what fluids or filters that need to be changed and consider how difficult it would be for me to do the task. I change the oil and filter, so most of the time, I have the dealership rotate the tires (until I get a nice compressor that accomodates air tools) for $22, including a wash. Thus far, at 24,000 miles, the only things that needed to be changed (besides the oil and filter) were the air filter and cabin filter. (every 15,000 miles, I believe).

I agree, but it sure does feel good when I occasionally rocket past a BMW X5 whose owner intended to pass me before cutting into my lane (instead of falling in behind me). The "ultimate driving machine" just can't get by the "ultimate technological wonder machine"! :whistles:

RX,

Your analysis of Lexus’s fuel octane recommendations in the O&M manual are not correct. Lexus says regular - 87 pump octane is acceptable and 91 pump octane is recommended. In the US pump octane is an average of ROM and MON. IE 87 pump octane = (91 ROM + 83 MON ) /2.

The proof is using the fuel. There is no knocking or reduced power as a result of using 87 octane.

Ron

Ron,

It is actually a bit ambiguous. The manual does not state that "pump" ratings are to be used, although this can easily be inferred by the nomenclature. The manual states "Octane rating of 87", but never mentions "MON" as an averaging factor. 87 pump octane does seem to work adequately during cooler ambient temperatures, but I would shy away from using it during the Summer months.

Dave

There are three choices of fuel grades. Mid-grade and premium are recommended in the manual. You will achieve lightly better performance when using premium, but honestly, few of us will be able to tell unless we are running our cars at the dragstrip.

Also, these are hybrid cars. If we didn't care about saving money (in the long run), we'd have bought X5s or RX350s!

How often do you use that window? I ask because this is a not-too-uncommon malady with some Corvette owners, primarily because they don't use their passenger-side window, much.

Believe it or not, there are Corvette owners who use mid-grade or regular fuel! However, should there be consequential damage and the dealership takes the initiative to analyze the octane in the fuel you use, the result may be a denial of warranty coverage. I admit that I have used regular gas during the cooler months, but I play it safe during Summer and use mid-grade. In the event that I do need to travel to areas that experience ambient temps over 100F, I will use premium.

Here's something you might want to read:

http://us.lexusownersclub.com/forums/index...c=38975&hl=

Dave

I agree!

Thanks for the direct comparison. A while back, another member asked that we include AWD or FWD in our avatar/info area on the left side of our post window. If you look at mine, you'll see the "AWD" letters.

Dave

There's nothing magical or difficult about getting 24-28 MPG in typical city driving. I've known two RX330 owners who were averaging 16 MPG in the same general area of town. Needless to say, they were not too happy when I told them we were getting about 25 MPG with our RX400h.

All the above being said ... you will only get about 5mpg better with an RX hybrid over a gas-powered RX (less if you are doing mostly highway/interstate driving) ... it just doesn't make sense financially to buy a 400h over the RX 350 given the gas savings PLUS the fact you will not get nearly as much off of the 400h compared to the 350.

This is certainly not true if you live or drive in a large metro area, like Los Angeles, San Diego, or any other similar city. We live 30 minutes from downtown San Diego, yet we encounter heavy trffic both in the morning and afternoon. Our minivan, which was getting about the same fuel mileage as would an RX350 (14-16 MPG in the city), required a fillup every week. Our RX400h, which achieves 27 MPG during weekly city driving and about 24.5 - 25 MPG after factoring 75 MPH highway use during the weekends, requires a fillup only every 2 weeks, saving us $40 per week. That's $2000 per year and $20,000 in the 10 years we typically keep our main driving vehicle.

Happily, we made the right choice when choosing between a hybrid and non-hybrid SUV, especially with pump prices as high as they are.

I would think that the warmer the climate, the greater the increase in fuel mileage from higher vs lower octane. If you are driving in cool/cold weather, higher octane wouldn't provide any advantage over, say mid-grade or even regular grades under normal driving conditions.

Saying that using super will always benefit you to that extent (+4MPG) is misleading. We average over 24 MPG using regular (Winter months) and mid-grade (Summer months). Perhaps during last week's heat spell when some areas of town saw 108 degrees, premium fuel would've been a good idea, but nnow that it is 75 degrees again, buying premium is not prudent, IMO.

Steve,

That was our reasoning, exactly. My wife needed something that placed her high enough to survey much of the road ahead, and my prerequisite was good gas mileage and plenty of luxury amenities. No other vehicle comes close in those regards. I did read recently that Porsche will be coming out with a hybrid Cayenne within the next two years. Let's face it, in the US, diesels are not very popular when it comes to passenger vehicles, much to the chagrin of the German car companies.

Dave

Both your Camry and Acura have a big advantage when driving at typical CA highway speeds - much lower coeficcient of drag. All Toyota-designed hybrids are running almost entirely on gas-power at cruising speeds, so I wouldn't expect a 4600 lb SUV to achieve much more than mid-twenties on a long highway run.

I believe there is a software download (at the dealership) to help fix any surging complaints. Our 2006 RX400h has had no such issue. In fact, in the 2+ years since we've owned this vehicle, my only complaint was the 30 psi tire inflation recommendation that is clearly labeled on the door jam. This pressure should be 35-36 psi.

I was under the impression that higher altitude means less-dense air, which would tend to reduce power and mileage. Perhaps it's the decrease in ambient air temperature that compensates for the lower density?