I'm fairly new in this PUA world, so take my feedback very lightly..
1) Seduce her with your eyes - maintain eye contact
This is so important when going for a k-close. What it comes down to is: start undressing her in your mind while you're looking her in the eyes. She will notice the difference.
2) Prepare her for the kiss - Qualify her
Something I've added recently to my game is qualification. Basicly, tell her why she is different than your previous dates.
ME: "Look, what I really like about you is that you are not as the previous girls I've dated. You have this fun vibe around you. And I really like that."
SHE: (will start behaving (more) FUN)
ME: (a bit later in the conversation)
ME:"Remember what I said earlier? That you have such a fun vibe? I just noticed it's more than just fun, it's even flirty at times. That's what seperates you from the others!"
.... now if you do it right, she should start loosen up & flirt more.
3) Kino kino kino
Use everything you can to kino her... you already mentioned you're holding hands with her & she was laying on your chest. Well man, it looks like you should escalate even more...
4) kiss closing at the car
I don't know how the situation worked out, but I would go for something like this:
1) depending on the mood you were in (I'll assume you had a fun day.. so I'll continue on this)... grab her hand and do something funny. Something as small as a little twist and get her closer to you.
2) Once she's closer, look really deep into her eyes (make this a little staring contest)
3) If it lasts longer than 3-5 seconds, act like you're going for the kiss-close, then 3 situations can happen:
A) she turns her head / mentions she's not ready yet... at that time you just continue your move and whisper something in her ear ("I really loved spending time with you." ... I wouldn't escalate too much here, because she's not comfortable enough yet)
B) she does not turn her head... she's obviously not afraid that you'll kiss her. Either you kiss her, or you whisper first and kiss her afterwards. Both should work.
C) she's kissing you back before you even can go for the whisper. GG.
My two cents, hope it helps!