over in frankfurt, the used car dealer marcel del arbol is too aware of the problem. main difference between them, one type of car sells well, the other does not. >> for the last year, prices have been falling dramatically along with demand. in some cases, demand has fallen 90%. the prices have plummeted. i reckon about 25% per vehicle. what has happened means prices will go down again. we have to see how things develop. i think sales will come to a standstill. >> carmakers marketed diesels as the environmentally friendly choice. they burn less fuel per mile and a minute less carbon dioxide. no wonder one in three cars on german roads is a diesel. car owners rely on them to get to work. manufacturers are confidence a general ban on diesel cars will never materialize. the car diesel lobbying group vda says even partial measures will be damaging. >> the decisions problem is different cities could have differing regulations. this concerns us because a patchwork of different r egulations would confuse drivers. that is why we hope for a reasonable, nationwide regulation. >