Of course detailing your car will improve its appearance. But, will it also increase the car's performance? I read somewhere that engine cooling fins would work less effectively when they are covered by dust.
That might depend, what are you thinking of exactly? I know some people that swear by it but few that can back the argument up. Keeping your car clean and in proper function allows it to do its job better. That seems like something everyone should know.
I could not see it increasing to a high amount. I think there is a difference when it comes to this, if you really want it to preform better you need to do larger type upgrades rather than smaller ones.