I'm not sure leaving your wallet in the car is necessarily any safer than keeping it on you. If you're really concerned, remove any extra cash and credit cards, but you may want to hang on to your ID. Some providers will ask for it as a means of screening and you may need it if the encounter goes pear-shaped and it's actually a sting. Keep a good thought.

I bring pretty much everything that I would normally carry on me. Unless of course I happen to have too much cash on me to feel comfortable, anything over a grand or so gets locked up in the car.

I'm no lawyer but in some states not being able to produce ID might land you in temporary custody. You could request to be escorted back to your car to retrieve your ID but then in some jurisdictions your car might then be seized under forfeiture laws. I can see not taking large sums of cash or credit cards to certain places (places I'd rather not go mind you) but I'd still take my ID. Years and years ago I took chances that required this type of thinking but with all the screening and planning information available today I can't remember the last time I felt like I was entering a potentially threatening situation.

Comes with me. Wallet, keys, donation and extra cash just in case I want to extend the session.  

and came to the same conclusion for the same reasons you just stated above.

...which means I take it all inside with me.
My fear of having my personal info stolen from my car outweighs any fear I have of bringing my wallet and personal stuff with me.

I bring my wallet and keys and I also dress nice with a nice watch.

Take the cannoli

and don't worry about what I take with me.  

Soap
Body Wash
Shampoo
I buy her cigs
Cash
My phon

Diapers
Milk
Bread
But not condoms

My wallet stays in the car. Cash and phone...that's it.  

have always left my handgun and binoculars in the car.  I couldn't think of a single scenario when I would need either one with a provider.  I always take extra cash in, especially with new girls, as I will often decide to extend the session if she is available when we have a good connection right out of the gate.

The rest stays at home or in the car or in the office for the first visit.
On the 2nd or 3rd visit, I will normally bring everything with me.  If I repeat with a lady, I trust her not to rob me.

but leaving valueables in a car, is not secure storage.  I reduced the un-necessary CCs & I carry my normal working cash (plus the donation).  I've never had a problem with any gal I've seen, valueables wise...  If I was that insecure, I'd cancel the date.  I AM careful where my valueable are & the gals have always been respecful of that.  
I do swap my TF in the belt carrier, & leave my RL phone somewhere in the car but mostly to lighten my load.

I bring my wallet, my phone and the Rolex on my wrist... like someone said.. If you have to worry, your seeing the wrong girls

The simple answer, of course, is: I take my pants into the bathroom and hang them on the hook there while I'm showering. Okay, so that keeps your wallet in check.  

There won't be any upselling. Phone for my safety, wallet stays in the car.

Because if someone sees me with them they avoid any contact with me.  I always leave my Rolex at home on those days.

If it's an incall, and I've not seen her prior, I leave all my plastic at home or my hotel room. I always have my wallet on me, it has my ID inside. I've never been rolled before, probably because I see reputable, well reviewed women. But you never know for sure if she might have a goon in her room and it's a setup. They can have the donation and chump change in my wallet, my DL doesn't have my SSN number on it, so that's all they're getting. I don't have a SO, so I will press charges, even though they don't know it going in, it's a lose/lose for them if they choose that route. It's a really bad idea for them to take my phone, it's way too easy to track that and besides it's electronically locked.

I'll admit that I haven't been doing this for more than a few years.  I'll also admit that the number of ladies I have seen is also relatively low.  The ladies I have seen so far - I just can't imagine it.  

and I am not worried about my wallet being lifted, or the few extra hundred bucks being stolen from my pants pockets while I am in the shower. I never have more than I can afford to lose on me, and I always know exactly how much, or within a hundred bucks of how much money I have with me at all times. I can't ever remember having a "well reviewed TER provider" ever once lifting a single cent from me while I was in the shower

If I'm parked in a residential area and for some ungodly reason I get towed, I'd be completely fucked without cell/wallet.

Depending on state law you may be required to present it if asked by law enforcement. In those states walking around without ID may increase your problems if you encounter LE.

Your wallet is no safer from thugs in the car than it is in your pocket.  Also, when the clothes come off, they remain in plain sight, so no provider could ever go through my pockets without me seeing.

my envelope and car fob

I bring anything needed for the activities and absolutely no identification lol