Does expensive car shampoo make a difference?

I am doing a charity car wash and asking ppl for a donation after so the cars need to be sparkling. I was going to buy tesco cheap car shampoo but if I will get a better result from high quality I might use that. Can any1 reccomend a good brand.Does expensive car shampoo make a difference?
You won't find much difference in car wash soaps, some may have 'conditioners' which are usually a petroleum based product that ads a temporary extra shine to the paint, but in your case quality workmanship is the most important factor of the wash. They won't see the extra shine as much as they will see what you've MISSED ! Do a great job and ask for a $15 suggested donation for just the outside and $25 if you vacuum and do the windows!Does expensive car shampoo make a difference?
meguiars gold class wash