I was looking to walk in with a Ceramic Spray Wax and spray it on the white car before driving it off the lot. But the ceramic spray wax needs water to start working - can't really hose it off at the dealer. So my question is, what can I do on a brand new car so I protect its paint (and shine) for the longest time possible? I am ideally looking to be able to walk in with a bottle of the product and a few lint free towels to protect the paint. Looking to do everything myself and avoid anything the dealer wants to sell in regards to paint protection. I am in Sydney (Aus), if that matters.
Honestly, doing anything on the lot is a waste of time at best and detrimental at worst.
New cars don't come in packaging so the paint is rarely in "factory fresh" condition when you pick them up, they've been shipped, sat at the docks, sat at the lot etc And in my experience they aren't often particularly clean - a cursory hand or jet wash is the best you can hope for. And if you're unlucky they've "cleaned" it badly with the same ratty sponge they've washed fifteen other cars with that day and you get a nice set of swirl marks included free of charge. I've known more than one person who has specifically requested that their new cars not be washed by the dealer prior to delivery, and honestly I can't say I blame them.
You're absolutely right to avoid any of the sealant/wax/protection packages the dealer offers - they are (without exception) hugely overpriced and more often then not applied in a slipshod manner by someone who either doesn't know what they're doing, doesn't care, or hasn't been given enough time to do it right. The old adage of "If you want something doing right do it yourself" most definitely applies here.
If you want to get a car looking and staying it's best the better approach is to take it straight home give it a good two-bucket method hand wash, light clay bar for any surface contaminants then buff clean and dry with a microfibre and then apply your protectant/sealant of choice.
Doing this ensures you're getting the "real" finish of the paint under the sealant and nothing else - and if there are any paint issues you can spot them and correct them at the time (or shout at the dealer until they do).
I keep cars for their life - until they don't run. I have never looked at one of the old cars and said "I sure wish I had waxed that car".
Half a century ago the metal used in bodywork and the paints applied were inferior. Some were so poor they would rot as you look at them. But those days have gone.
Not only that, but getting wax on the windshield can be positively dangerous. When it rains and you use the wipers, the rain smears so you can't see through it at all.
I rarely use an automated car wash, because even if I select a non-wax program, residual wax on the rollers still gets on the windshield. And when I buy a car, the exterior has been "helpfully" waxed and the interior is coated with slimy silicone. All of which takes a few hours to remove.