Hero33 actually says it all. Being too common can cause a car to not be that prestigious or exclusive. Imagine if you bought a new 3M peso car and some guy drives besides you with a 10 year old (same) model at a stop light. Winks or waves at you in a sign that you're both same model owners and leaves you in the dust of his exhaust. That isn't exactly how I'd want to spend a small fortune on a car, which too many people have. I'm not saying it doesnt drive well or the car isnt great but there are just too many on the road. Think of it as too many people having good taste. ;)
Even though the Benz (as a brand) ranks high on Fifth Gear and Tsikot it ranks 9th from the bottom on the JD Powers Customer Satisfaction ranking of 2004. In 1994 Benz was #1 on the same Customer Satisfaction survey. That's how much exclusivity and prestige can help a brand sell cars that are worse than some of the most looked down cars in the world. This year though Benz appears to have jumped back to 5th place.
The Bentley and Rolls Royce are indeed more prestigious than those cars listed above but then again those uber brands dont offer entry level executive cars.
BlueBeemer is correct this survey was done on this week's Fifth Gear. I was curious how Tsikot peeps would rank each one. The Brits and Pinoys taste in cars are pretty close.