Car & Driver's Long-term Rx400h

[RX400h]

After driving a 2006 RX400h for more than 40,000 miles, Car & Driver managed 24 MPG with many a lead foot and 27 MPG after being driven by editor Pat Bedard in Arizona for four months. They did make a couple of mistakes in that they assumed premium gas is required (we all know THAT is not true) and they calculated payback of extra cost based upon gas prices of $2.39/gallon. Here in California, even regular gas is costing us almost $3.00/gallon.

Regarding the blazing 0-60 time of 6.6 seconds, C&D commented that the Rx400h is as fast as a 340-hp Porsche Cayenne S. This time is definitely better than that possible by the RX350. Some of the drivers noted that the transition from all-electric to gas&electric was not always smooth and that "the transition from regenerative to hydraulic braking was often disconcerting because a small increase in pressure on the brake pedal might produce a large increase in deceleration."

That's kinda funny because I rented a Maxima for one month, a couple of years ago and I can assure you that the super-touchy gas pedal response was FAR more disconcerting tha anything an RX400h can do!

In conclusion, C&D wrote, "Despite its quirks, our RX400h turned out tobe a spry and fuel efficient luxury SUV, which is a rare combination in this price segment. For some people, that will be more than enough to justify the premium over an RX350."

Dave

[RXREY]

Great post,thanks.

Let me just ask,

I can run my 400h on regular unleaded? Have you noticed any difference in mileage, power? I've only ever put in Chevron premium. Rey

[RX400h]

According to our manuals, "Select Octane rating 87 (Research Octane Number 91) or higher. For improved vehicle performance, the use of premium unleaded gasoline with an Octane rating of 91 or higher is recommended."

The octane numbers many of use see on the gasoline pumps are an average of motor octane number and research octane number.

"What octane number should you buy?

Modern fuel-injected engines have engine management systems that can adjust to burn almost anything. However, if the octane rating is too low, the engine management system will have to richen the mixture and !Removed! the timing to prevent destructive knock, resulting in lowered gas mileage. As you increase the octane rating of the fuel, you will hit a point where the engine management system can run the engine at optimum levels. At this point you have best gas mileage and best power. If you continue to increase the octane rating of the fuel, the engine management system does nothing, so all you are doing now is burning more expensive fuel for the same result. So, buy the lowest octane number that you can and still get your best gas mileage.

In the winter, or when it's very humid, you can often lower the required octane number. In very dry heat, for example in Texas, New Mexico, Arizona, S.California, you will most likely need to raise the octane level a bit to get best gas mileage."

This is also true of my Mazda MX6-GT turbo's fuel requirements. Even though 91 octane gas will allow the engine to produce maximum horsepower, using lower octane gas will not hurt the engine as long as its knock sensor is functioning properly. As the statement above indicates, driving in colder weather allows many vehicles to run perfectly well on regular (87-octane) fuel.

I have been using 87 octane gas for almost two years now and have never heard any pinging or experienced any problems. Power is more than adequate. However, during Summer, it may be wise to use higher octane, especially for trips to cities like Las Vegas.

BTW, we average 25 MPG consistently and that's with my weekend heavy foot-driving.

Dave

[Rx330driver]

that 0-60 time seems a little fast dont you think? its a bit over achieved. Im not saying they didnt get that, but saying that an RX350 couldnt get the same time is a bit biased.

Granted the hybrid has torque at 0 rpm, i cant see it "competing with the porsche"

[Jim Nazium]

that 0-60 time seems a little fast dont you think? its a bit over achieved. Im not saying they didnt get that, but saying that an RX350 couldnt get the same time is a bit biased.

Granted the hybrid has torque at 0 rpm, i cant see it "competing with the porsche"

Your right, the Porsche better come with some NOS so it can at least get out of the whole in one piece.

[RX400h]

that 0-60 time seems a little fast dont you think? its a bit over achieved. Im not saying they didnt get that, but saying that an RX350 couldnt get the same time is a bit biased.

Granted the hybrid has torque at 0 rpm, i cant see it "competing with the porsche"

The RX350 did 0-60 MPH in 6.8 seconds - not shabby, but not as quick as the RX400h, which has axle torque equivelent of 650 lbs-ft - MUCH more off the line than that of the RX350.

[RXREY]

I had a RX 350 as a loaner when my car was being serviced (my 400h is pretty new at one year old so that means I've only had a loaner twice) , initially the 350 has a real,"pull you back into the seat" that is not present in my 400h,but that's it. After that the 400h smoothly but very quickly gains in every other way. Does the RX350 have the continuous drive transmission? It didn't feel as smooth as the 400h. The 400h is faster and smoother by far. I am always glad to get my 400h back. One thing that makes it so much more effective is the lack of the belts that lug the engine in conventional gas-only cars. But as long as it's a Lexus, we all have a great car! happy trails. Rey

[Rx330driver]

no, the RX350 is stuck with a 5 speed :(

[LexRexBlue]

I have had my RX400h for over a year and a half and ran it almost exclusively on regular. I did check with the service advisor at Lexus first. However, I noticed that when the weather is extremely cold that I was getting terrible mileage. Since the hybrid guide given to me at the Lexus Hybrid event suggests using premium to improve mileage, I tried it. The difference isn't so much in just cold or warm weather, but when it is very cold as it is now--10 degrees, it seems to get at least acceptable mileage on premium. Id' say about 4 mpg better. When the weather moderates I'll try switching back and see what happens. Mathematically, if you can get significantly enough better mileage with premium it's worth it. Now that the price is creeping up, I may have to rework my figures!

[RX400h]

Typically, premium is required for high-compression engines. You'd think that the RX engine doesn't need to have bumped-up compression, since it is supercharged by many kilowatts of power. Regarding ambient temperature and its effect on the grade of gasoline that is required, I recall driving in Las Vegas in our Nissan Quest when the ambient temp was up around 110. The V-6 engine pinged horribly on regular gas. When we returned home to San Diego, the engine ran great (75-85 degrees F).

This is why I am surprised that LexRex was getting lower gas mileage during cold weather months. I wonder if friction had something to do with it?

[SOMEONE ELSE'S GOT MY NAME]

Great post,thanks.

Let me just ask,

I can run my 400h on regular unleaded? Have you noticed any difference in mileage, power? I've only ever put in Chevron premium. Rey

We use both on occasions. Some of the cheezy regular in MT will cause pinging. When up there, we use mid or high test to avoid the knocks.