Washing in supermarket carparks! (BUSINESS)

Being clean is one of the most important feature for people in now days. Then should they also clean those things that they own clean? For example, do they even have to clean their vehicles even though it is not those owners who are being clean? The answer is of course YES. Because those vehicles not only represent the owner of the car but also represent the beauty of the modern street. Here is really good business idea which in China according to my Chinese friends, they already have these kinds of business that those shop-owners wash the cars of customers under certain fees while those customers are shopping in the supermarkets. This business idea gives me 2 good factors about this; saving time of customers and offering cheaper prices for washing the vehicles.
In these days, a lot of people are looking for really useful business ideas. But the thing is that this kind of business idea would not work unless it is really useful for customers at the point of certain time. As I talk about those useful business ideas, I think this business idea is really useful. Because as I said earlier, people always want their cars to be even more clean than themselves sometimes. And a lot of people who works daily until late night do not have enough time to wash their cars. So this business idea firstly solves 2 problems of customers at once. This business idea not only saves customers time to shop and wash their vehicles since they are washing the cars for them and also makes those cars clean!!! This business idea not only have this crazy feature but also have really good offer of cheaper price to attract customers.
What would be the second best option that those customers would consider after they see about the quality or whatever things they need? I think it would be definitely cost of doing something. I believe this business idea would offer really cheap price of washing the cars for them. Because those shop-owners can make profits out of selling their products and can also make profits by washing those cars for them. So if I were the business idea owner, I would use this washing idea as a kind of lossleader but still makes profit. I mean, if they lower the price of washing cars little bit lower than the normal price, then people would come to this shop to wash it more often and if they come, they will buy things at supermarkets, so produces can also make profit from it.
As I said in the introduction, this washing vehicles at supermarket carpark is really brilliant since it considers two main factors; low price and saving times of customers. This business idea will be even more great if they do not have problems such as need of more workers and places.