Stupid Question Re: Highway Speed
 

OK, here's a question I feel stupid asking, but I'm not an aerodynamics guy, nor a performance car guy...

Why does my '95 E320 ride smoother at 80MPH than at 35MPH? Is it just an illusion? I haven't had the car for long, so I still don't take it for granted. I always have the feeling that 80MPH somehow "feels" slower than 35-40MPH? At lower speeds, it feels like a nice car; at higher speeds, it seems to stretch about a foot longer, six inches wider, and ride like a big cruiser.

Anybody got opinions about why I get this perception?

I enjoy driving this car at normal speeds on city streets, but when I get on the interstate, in the middle of the desert, and start cruising, my grin gets wider and wider and...

See - I told you it was a cheesy question.

Re: Stupid Question Re: Highway Speed
 

Every properly maintained Mercedes-Benz I have owned or driven has been extremely stable at highway speeds (everything from a 190E 2.3 to a Maybach 62).

What were you driving previously?

These cars were designed to go flat-out on the Autobahn for long periods of time. So the chassis and suspension is set up on the "stiff" side for high-speed stability.

While this type of setup offers a smooth stable ride at high speeds, the trade-off is a less-compliant ride at slower speeds. So you feel every bump and road abberation when going 35-40.

The "abberations" flatten out at high speeds, making it seem you are just "cruising" rather than "driving"...

you have learned the joy of having a german car my friend:D If you really want to live see how they settle in past 100 ;)

the suspension springs and shocks of the car are tuned for high speed - this means that they are optimized for that speed.

at high speeds, the impact forces on the suspension are much higher, as well as the frequencies of such impacts. To deal with these without upsetting the chassis, you need stiffer springs and shocks (i.e., relative to what you would normally consider "luxurious" in city driving). Also, all Benzes have long-wheel-travel suspensions, allowing the suspension to soak up large high-speed bumps without bottoming out.

If you had a soft suspension and you were travelling at high speed, you would experience too much wheel travel, the suspension bottoming out, and the vehicle being less controllable - which, from the driver's point of view, are not very confidence-inspiring.

additionally, even the spring rates of the seats are tuned to the suspension setting, and that's one reason why the seats are hard.

the tradeoff of these is that you get a bumpy ride around town.

this is the motivation for active suspensions - at low speeds, the spring rates (e.g. air springs) and shocks are set to a compliant mode, and are progressively stiffened as the vehicle speed increases.