There are many, many, many soaps out there.
The main problem that people out there experience is the electrostatic bond that the dirt/grime makes with the surface of the vehicle.
Here is an example: You can be at the local car wash and spray soap all over the car and start using the power washer but most of the dirt does not come off, even when you put the spray closer and closer until the spray nozzle almost touches the car but still, not all the dirt is coming off. You wipe it with your finger and it comes off so you try again with the pressure washer and still no more comes off so you wipe it with the finger again and more comes off.
What happens is as the vehicle is driving down the road there is a buildup of static electricity on the vehicle and the dust, dirt, soot, contaminants, etc.... get stuck to the vehicle and are hard to get off.
There are ways to remove this, with chemical 2-stepping or brushing with a good soap or using a wash mit with a good soap. You need friction (brush, wash mitt, wash glove, etc....) along with a good soap and it will remove the contaminants.
Just spraying soap onto the vehicle that has a buildup of road grime and rinsing will not do much, if the car is just dusty or is washed weekly then the soap and rinsing might do the job.
That is one of the reasons that at just about all the car washes there are the guns/wands and also brushes that spray soap out of them, you will need to brush when the car is very dirty, the car wash companies know this and so do the soap manufacturers.
There are some stronger soaps out there that will remove more of the contaminants but the regular car and truck paint, clearcoat and wax are not designed to be used with the stronger soaps and can damage the paint where the over the road trucks have a stronger paint that is very durable and can usually handle the stronger soaps.
Hope this helps.