Let's just say I've been taking notes on things during my time here thus far. This list will be periodically updated to add new suggestions.
Ideas for potential improvements for NFS:SA
1) add option to enable/disable cops
2) add minimap icons for dh diamonds and unique car parts (also make this toggleable)
3) change car reputation system to max out at 5 stars (Mag run requires 3 star car, I like the user below me's idea of greater rewards for 4 and 5 stars respectively)
4) change custom race UI to fill screen, add track map and possibly best times
5) remove dyno from game or tone it down so cars don't constantly need buffs/nerfs and score system actually works (limit it to gear ratios and other minor changes)
6) add revlimit noise when top speed is reached
7) change race UI to more closely resemble nfsu2/carbon (or add customizable race UI, i.e. I'd love to see Gran Turismo 2 UI)
8) add scheduled races/events to drive to on map, similar to URL but smaller scale (single race/drag/street-x,etc.)
9) change url scoring to make it so you are rewarded 1 point for DNF/change scoring to be based on distance travelled or laps completed (this was also a suggestion in another thread, added here since I agree)
10) add customizable soundtrack feature (I would personally change the playlist to just nfsu/u2 songs)
11) add tabby speedometer from nfsu2 (The only one from there not ported I believe)
12) add tutorial level/pop-up boxes with information, especially about dyno
13) force beginners to complete at least 3 quick races before going into custom race lobby (I know this was in another thread, I saw it beforehand and have added it here since I agree)
14) add user-created tuning database to forums/game, akin to gran turismo forums
15) force beginners to read rules after selecting their first car (which involves making them scroll to the bottom before they can proceed)
16) change UI windows to be less plain, see first picture
17) add option to not save magazine run photos (this gets annoying after you play 20 in a row, get to run and it tells you you can't do it until you delete some. why do they even save in the first place??
18) add option to exchange vinyl points for money or body points (preferably 2 VP for $500 or 1 BP)
19) add user-created vinyl design database you can import/download from (?)
20) A screen to change dyno tunes and equipped parts on the fly (SEE 3rd PICTURE)
21) A quick menu like the Motorola interface from NFSU2 that would make a noise and quick-press icon for duels and entering shops and dealerships, gives the ability to check PMs recieved, check/delete magazine run photos, do the functions of the function keys, etc.
22) Remove ambient shooting noises in LS (just a minor annoyance)
23) Add colorable calipers to brake discs
24) Have max speed testing done in the dyno garage, like NFSU2, with possible hp/torque, hp/rpm graphs (vehicle will accelerate until speed stops increasing, and spit out top speed value)
25) Add cruise control hotkey for travelling repetitive trips to DH/Mag Run (obviously enable this option for freerun only, disable for Pursuit, DH, Mag Run, Duel)
26) Remove/minimize destructible objects and indestructible wooden poles (NFS does not have these disruptive objects, the world should be friendly for a driving-only game)
27) add option to choose which safehouse to warp to when you press F6
These are just my thoughts I've been putting together over time. Don't know about the plausibility or thoughts on these ideas from the community, please submit your thoughts below.
Also included are some pictures I made.