First, I HAD a 1998 C230, got totaled one-month ago, fantastic car, great gas mileage, built like a hand-built car, and performed like a champ in the accident.
I purchased a 2002 C240 new, but used it very little, 18K miles in seven-years.
Now that I use the car full-time, it makes the W202 seem very aged.
As far as CLASSIC and ELEGANCE you SHOULD be able to find the differences at the Mercedes factory web-site (maybe better luck at the U.K. site).
I did have some electronic teething problems when the car was new, a sensor in the car for the infra-red key was replaced, and the notorious ESP error occured - meaning new wiring ends -
www.mbwholesaleparts.com under STARTECK INFO has articles about this.
Actually my car has been very good, these cars like a fresh battery, a mediocre battery cause all kind of driveability issues like transmission shift points, maybe even caused some bulb issues in the driving-lights can't remember exactly what happened, but know I has to change a few different bulbs, not all at one time, but now no more bulb issues.
My C240 gets great gas mileage as stated by the on-board computer, something like 32mpg on the highway at 70mph with smooth pedal useage. City, suburban gas mileage is not as good as my 1998 C230.
Car is very quiet, wind noise really isn't noticeable until about 70mph, the Michelin Primacy tires I run are super quiet. The HVAC has a gear in the dash which some people have had issues with, mine works great, you can hear the gear hum when working and it makes a noise during start-up and after ignition is turned off - this seems normal.
The suspension and steering are nothing like the W202, at low speed the car is very luxurious riding, at high-speeds the handling is very composed - and at very high-speed I think you probably have increased grip but the W203 seems like if it did lose rear end traction at high speed it would be very abrupt and I think that I wouldn't be able to recover. I know that sound wacky - but what I'm trying to say is the C240 is very fast and very confidence inspiring and it is way easy to find yourself entering sweeping turns at crazy speed.
The 2002 C240 has a wonderful dash-display - changed I think in 2005, now that I've lost a few pounds I find the seats much more confortable- I used to get lower back ache during long 100 plus mile drives.
The automatic transmission is SLICK, I used to think the traditional gated Merceds automatic selector was all class. Presently the side wack activation for up & down shifting is a real treat.
You got to drive a dozen or so test cars to know what is normal, but a nice C-240 is a great car. My opinion is it's the nicest car out there except for another higher level or newer Mercedes, I think the Porsche Caymen has the ultimate combination of pedal (gas, brake) to suspension relationship - dynamics, but I think Mercedes is more reliable with stronger engines and fuller-proof transmission ( rear main seal ) production.