But you don't sell many Dodge badged cars in Europe. Motor Sports, for manufacturers, are above all a way to make your brand known, respected and appealing. The FIAT guys may be italian and, as many italians, may think NASCAR is a lesser form of motorsport. But ... nobody is saying they want to enter this series as FIAT. It is DODGE we're talking about and, regardless of who owns it, they need/want to sell Dodge cars.
The way I see it, They think the GT Viper is what they should be promoting, not a NASCAR car. I agree, but then again I'm european and I'm not sure what kind of motorsports is more effective at making cars sell in the USA. In the end, that is the reasoning behind the decision of staying, or leaving, F1, GT, Touring, NASCAR, whatever.