Audioquest Golden Gate or Big Sur mini-to-mini cable for my car use?

Good call

the mini RCA to mini RCa cable link is not the Raod to OZ most  important link for headphone or car audio.  Instead, an investment in a quality build mini- DAC/headphone amp, an APPLE  camera lightning to USB converter (if required) , AND a high-resolution player app to go along with a mini-RCA cable is a better upgrade path. The AQ mini-RCA cable performance difference between your models in a direct bake-off is negligibleto nil.

why?

(1) the “standard” internal phone DAC is a cheap comparative  low level part and low-level audio performer available to be bypassed with an external mini- mini-DAC/headphone amp capable of hi-Rez digital file playback

(2) the “standard” internal phone player app is likewise a low level minimal quality and comparatively poor performer lacking hi-Rez output, that can be supported,anted with a new player app capable of hi-Rez playback.

- The external USB MINI- DAC (and Apple camera Lightening to USB converter if required for IOS) 
https://www.wifihifi.ca/LatestNewsHeadlines/Hands-OnReview:AudioQuestDragonFlyBlack1.5/Red.html

- the hi-Rez player app available via download 
(a) ONKYO HF PLAYER for iPhone or Android
(b) TEAC HR AUDIO PLAYER ...ibid...

If it’s SIRIUSXM or AMAZON MUSIC, ( I use TIDAL which has a hi-Rez option as well as “ standard” compressed MP3 ...I’m not a S or A subscriber ...) they appesr to be the latter ultra compressed MP3 level formats

if if so then a hi-Rez upgrade in hardware or software is a noble thought but a playback upgrade waste if you are only dealing with a low-level compressed streaming digital format steaming over the air .
In direct non-hi-Rez (320kps) mode digital file playback directly to the car input , the 3.5mm mini-RCA cable upgrade from a “standard” link suffers also a similar fate.

HOWEVER, IF HAVE A LEGITIMATE HIGH RESOLUTION SOURCE FROM STREAMING OR DIGITAL FILE DIRECT PLAYBACK

I have a top WIREWORLD 3.5 mini to mini RCA cable in my hi-Rez playback. It’s a big step up from cheap throw- in phone accessory IFF with the AQ Dragonfly / Onkyo Hi-Rez app ensemble, AND (emphasis added) HI-REZ format input.  The audio playback performance improvement on a hi-Rez source file (TIDAL for streaming, or resident on my iPhone) is not subtle.

my take

Unless you choose to eventually upgrade and adopt a different full high-resolution digital streaming source (a la TIDAL) or a direct hi-Rez recorded digital file sourced and resident on your phone , then stick with the basic cheap setup and accessories.