Has anyone noticed the front gets light feeling and looses a bit of solidity at 110 mph or higher. should these cars have sufficient aerodynamics for high speeds. My c32 was great all the way to 155mph. freaks me out.

need to add 4 more psi on to the tires when you are going 100+ mph

Get a front lip that should help then tested by San Onofre Nuclear plant, plenty on highway and no cops.

wait, C300 goes how fast max?

I think we are electronically regulated around 135? I've only been up to 120...
RP

When you put those big 19s on there did you also drop the suspension? If you dropped the rear a bit more than the front, that could cause a bit more pressure underneath the car. A deeper lip spoiler would help but it may be more wheel/tire related that aerodynamics.

Wouldn't a rear spoiler also increase the tendency for the front to lift?

Hmmm, good question.

Have you messed with the suspension? - These cars are designed to be nose down - On all these forums I see people dumping the tail of the car too far. This allows too much air under the car at speed & messes with high speed stability. The 203s & 204s don't get light at speed if set up correctly. i.e. attitude = nose down tail up! Might look good with the tail dumped but it wrecks stability.

it is still very solid when i hit 120.. pretty impressive for an entry level car

c300 4m tops out at 132 - 1mph faster than e350 4m...

+1!

Must be something wrong with the car, my C200 CDI is rock solid stable at 120 mph on the Autobahn. Actually feels like it was designed to drive like that all day (and it probably was). Strange in fact how this car seems rather noisy at 80 mph, but then stays exactly the same when running at 120 mph.

Wow thats pretty good hahaha

No problems that I've noticed at upper speeds... Check out your PSI. Top speed for me was right around 133, then the electro-mommy took over the throttle for a few seconds...

German fast cars (excl. Porsche) are regulated to a max. of 250 Km/H (155 MpH).

So you should be getting at least 155 mph

Nope.... This is a US-spec C300. I believe C350 might have a higher speed limiter.

That was a sort of "Gentlemen's Agreement" for many years but a lot of the high end models have jumped well above. As far as I know, most "regular" but still stout cars are relagated to 155MPH.

Yep, this was my experience during my post factory delivery trip on the autobahns. My 2009 C350W cruised effortlessly at 110 MPH, totally composed and very quiet. Other cars I have owned may have been a bit quieter a moderate speed, but the Benz stays quiet as the speed builds up.

I also noted that steady speed MPH actually increased (per the onboard consumption display and actual miles/fuel used measurements) and peaked around 90 MPH.

And "nope" to that too! 133 is the limit for the US spec C350 as well. And with the tire pressures correctly increased for the higher speed, it's rock solid with no front end lift or hint of instability.