Engine Noise. How To Deaden It?

[JasonATL]

After driving the RX 400h for about 1600 miles over the last 8 weeks or so, I had noticed the engine noise (during anything but gentle acceleration), but it wasn't all that bothersome... until I drove my old 1999 RX 300, that my wife now uses. I was amazed at how quiet the RX 300 was compared to the RX 400h.

I'm sure others notice this -- I've seen it mentioned in pro reviews of the vehicle.

So, now I'm wondering what makes the engine noise in the cabin so much worse than the RX 300. Is it because of the trasmission that the engine is just louder? Or, to save on weight, did Lexus lessen the insulation/thickness of the barrier between the engine and cabin? The latter is fixable (in theory) using aftermarket products, albeit at some cost in weight. The fact that this only occurs during relatively hard (but not that hard) acceleration leads me to believe that this is a transmission issue.

Is this something I should complain to the dealer or Lexus about. In living with the car for a while, this is probably my foremost complaint. One of the things that made us love our RX 300 is that it is/was the one of the quietest SUVs around -- as quiet as a car. I can't say that about the RX 400h (unless, of course, the ICE isn't running!).

Any thoughts?

[bv2]

I too, have noticed slightly more acceleration noise in my new 400h--- but I'll tell you what--- when you hit the accelerator, the car actually moves--- unlike my old 300. I will take the brisker acceleration with the minimal acceleration noise rather than poor pick-up anyday. I am very pleased with my new car so far.

[patt]

From what I've read, Lexus did more sound deadening on the RX400 than they have on the RX330. The article mentioned things like sound deadening windshield glass. Ours is pretty quiet. It is quiet enough that I have to be careful to watch my speed because the noise level at 65/70 is significantly lower than that in my Camry and it is easy to let the speed creep up without realizing it. I haven't driven an RX 300 so I can't comment on the comparison.

[katzjamr]

The 400h has more sound deadening material all around the cabin than any rx before it. Lexus had a concern that people would object to whine of the electric motors, to the point that they put in a laminated windshield to reduce that noise source also. As you surmise, your engine and transmission noise is throatier under heavier acceleration, its not a noise that bothers me, and was clearly there during the three cars i test drove. For me, i am aware of tire noise on different road surfaces much more than engine drivetrain. My dealer told me to turn up the sound sytem (just kidding)

[RX400h]

I think the noise may be coming from the electric motors, not the engine. High-powered electric motors tend to be very noisy. Fortunately, the noise surfaces primarily while heavy throttle is being applied. Cruising is very quiet.

[LexKid630]

I have had my Rx400h for a few weeks now and also notice that, overall, it's louder (except at idle) than any other Lexus i have owned.

I have no idea why it's louder, but i wish Lexus would do something about it.

[JasonATL]

I agree with at least two observations of others: 1) the power of the 400h is unmatched by that of the other RX (300 and 330). So, the noise is not a cost without some benefit. 2) At cruising (and at idle), the 400h is very quiet.

So, does this mean that any further attempts at sound isolation in the cabin would be fruitless?