SW17LS

It comes from having driven MANY similarly priced and spec'ed sedans and SUVs in an effort to try and decide if I could handle going to a SUV/crossover vs a luxury sedan for my primary vehicle. Like I said, SUVs sit higher off the road which helps with road noise, but they also are less aerodynamic which increases wind noise, they have larger interior volume which hurts efforts to dampen noise, they tend to have coarser powertrains in my experience. There are gives and takes.

I've basically driven everything that is a luxury SUV/crossover and everything that is a luxury sedan. No question in my experience overall sedans are quieter than SUVs/crossovers. For instance, I have driven two SUVs that I felt were as quiet as my LS460, a full Range Rover, and the new Audi Q7. I have however driven multiple sedans I feel are as quiet.

Johnhav430

If I had to have guessed, I would have thought it was designed in California.....I envision people on the beach bench pressing heavy weights, Austrian accent maybe, etc. I mean cool was the objective....I think they missed but maybe the audience is not me.....

jrmckinley

Gotcha and understand now. Yes, the taller height certainly doesn't help with aerodynamics and therefore wind noise. I also assume the size of the tires may be a factor as well. At highway speeds, our LX570 is almost as quiet as our LS460 (I like this comparison since they are both the "flagship" model within the same manufacturer across 2 different categories of SUV and sedan). I think the minimal difference in overall noise is attributed to the wind from the height of the LX and probably tires as well.

peteharvey

Only when you're stationary at the traffic lights in a Mercedes GLC and a garbage truck stops directly behind, we can hear all the loud ticking of a diesel engine directly through the GLC CUV's poorly sealed tailgate.

peteharvey

Yes, the taller the vehicle, the greater the compression of lamellar air resulting in higher air pressures around the canopy, roof, windscreen and windows.

SUV wagons also have larger rolling diameter tires where the overall unsprung weight of the wheel-tire combination is much higher such that when the SUV wagon wheel-tire combo strikes a bump, much more "momentum" and impact force is imparted to the body of the motor vehicle.

mmarshall

Added to unsprung weight, of course, is the mass of extra driveshafts/hardware with the AWD that SUVs typically have.

SW17LS

That type of extra weight improves a vehicle's ride...it doesn't detract from it. Totally different from the issue of unsprung weight.

peteharvey

However do remember that while an LS has a larger wheel/tire unsprung weight combo, but a much heavier sprung body weight, a typical SUV wagon deliberately uses a much larger rolling diameter tire in the interests of a much higher ground clearance, such that its unsprung to sprung weight ratio will be higher than the equivalent sedans.
Hence when we test drive an RX compared to an ES on the same platform, the RX always has a "knobbier" ride due to the much greater unsprung weight of the bigger wheel/tire combo.

SW17LS

I agree, and you see this with most crossovers/SUVs vs sedans.

mmarshall

Incorrect. Half-shafts and U-joints/CV joints, whether front or rear, even with IRS, are usually below the suspension.....they move up and down with the springs. Now, the differentials, yes.....you're correct. They are not part of unsprung weight, except with traditional live axles.

SW17LS

It is not incorrect, you mentioned driveshafts specifically, the heaviest component of an AWD system being the transfer case, that is not unsprung weight.

mmarshall

OK...I meant half-shafts. Call it a typo on my part if you want, but half shafts, in fact, are usually unsprung weight. The extreme example, of course, was Ford's primitive Twin-I-Beam truck front suspension...the heavy crossbeams (like super-heavy half-shafts) pending on the bottom of the springs causing a lousy ride.

A little off-topic,maybe, but all this talk about unsprung suspensions and ride quality makes me glad I've got a nice cushy Lacrosse on the way LOL.

peteharvey

Yes, half the weight of the drive shafts, coils, shock absorbers, and suspension arms belong to unsprung weight.
The full weight of the hubs, brake rotors, brake calipers, wheels and tires belong to unsprung weight.
The weight of the engine, clutch, gearbox, propeller shaft, front, center and rear differential, engine & suspension subframes, and chassis - all belong to the sprung weight.
The heavier the sprung weight, the lower the frequency of oscillation after hitting a bump - similar to a heavy rifle, or a heavy baseball bat with less recoil velocity.

SW17LS

Correction, half shafts. In a fully independent suspension car the driveshafts are unsprung weight.

mmarshall

Yes...agreed. That's why the old American luxury cars used to ride so smoothly. They weighed from 2-3 tons, had relatively small (though stamped-steel) 15-inch wheels which cut down unsprung weight, and relatively soft suspension and spring-rates.