SL1R does not explain anything! This guide does, though!
Not a full list! Self-explanatory options skipped!

Though sometimes renamed, most of SL1R's settings are equivalent to those seen in the original game.
'VERY LOW / VERY HIGH / ULTRA' levels have been added for some, check for them!
Warning: Higher levels can have a major performance impact even on modern systems!

LMB to go forward, RMB to go backward, or use arrow keys.
These controls work with settings that have sliders, too!
Click slider value readout to manually type the value.
Right-click this to reset to default/previous value.
This works with ALL sliders in SL1R!

DAMAGE LEVEL
Same as DIFFICULTY LEVEL of the original game.
NORMAL = SL1 MID, AMPLIFIED = SL1 HIGH.
Damage system is designed for MID, HIGH was never the intended way to play, with small bumps doing absurd amount of damage, hence the rename.
In SL1R, the setting also affects how quickly parts lose health on impact, not just deformation & wear rate.

EXTREME WEAR MODE
Additional wear multiplier, for extra challenge!

To clarify, "wear" is damage taken from use (tyre slip, braking, violent suspension compression, high engine loads & RPM, etc...), this does not influence damage taken from impacts!

TRANSMISSION
Arcade Auto = Hold brake to reverse. (Same as SL1 Auto).
Simulation Auto = Hold brake to hold brake; Switch to reverse to reverse. (Same as SL1 Semiauto).
Manual + Autoclutch = Clutch is automatically applied for starting the engine, and to prevent stalling.
Manual + Clutch = Allows stalling. Despite what you might expect, use of clutch is NOT required for changing gears.

LIGHTWEIGHT TRAFFIC
Reduces the mass of traffic cars to 1/20th of normal, making them easy (and fun) punt out of the way. Also makes for more competitive racing, as neither you nor the opponent will be wrecking as often.

TRAFFIC DENSITY
NORMAL / HIGH / RUSH HOUR are equivalent to LOW / MID / HIGH of the final SL1 version.
LOW / NORMAL / HIGH are equivalent to LOW / MID / HIGH of older SL1 versions.
NORMAL or HIGH are recommended for best gameplay.

PEDESTRIAN DENSITY
Very CPU-heavy, lower settings recommended even on modern systems!
Note: Pedestrians are important for career progression!

SCREEN RESOLUTION
'x 32' / 'x 16' indicates color depth. 16-bit color may improve performance on (very) old GPUs.
Reducing resolution will also increase font size, as text uses pixel-based scaling.
Wider aspect ratios will increase the amount of per-page inventory & paint can slots in garage.

SHADOW DETAIL
Resolution of dynamic shadows.
LOW = 128x128
(256 .. 512 .. 1024)
ULTRA = 2048x2048

SHADOW RANGE
At what distance dynamic shadows become visible.
Distance depends on object size.
Distance on an Axis:
LOW ~= 14m
(~28 .. ~70)
VERY HIGH ~= 140m

VIEW RANGE
LOW = 50m
(100 .. 250 .. 400)
ULTRA = 600m
Due to dense fog normally making it unhelpful, ULTRA is only active with COLD MORNING ALPHA weather, normally acting as VERY HIGH instead!

WEATHER
Visual style of Test Track & Valo. Does not affect simulation!

WEATHER: COLD MORNING:
Default SL1R look.
Max fog density scales with view range, up to 300m.
Max view range: 400m.
(View range: ULTRA / MID)

WEATHER: COLD MORNING ALPHA:
Look matching old pre-release SL1R versions (seen in the old trailers).
Fog scales uncapped with view range, reduced density near camera for a more colorful look.
Max view range: 600m.
---

WEATHER: SUNNY:
Classic SL1 look.
Max fog density always at 130m.
Max view range: 400m.
---

FOV
Field Of View - widen for increased 'sense of speed', and to see more side-to-side.
Reduce to see better into the distance (helpful for driving well!).

VOLUME
Self-explanatory, right?
Yeah, about that... :D

The game will not play sounds which it doesn't consider 'loud enough';
If you turn these down too far, sounds will start to go missing altogether, so it's recommended to adjust master volume via Windows instead.

LOOP MUSIC
Most SL1 music is designed to loop! Disable this if you've added custom music!

TRACK SELECT
What to do when a track ends or music set is changed?
MANUAL = You must change track yourself using the "RADIO STATION" binds.
CYCLE = Select next track.
SHUFFLE = Select random track.

MIXING
Audio processing mode.
SOFTWARE = Use CPU.
HARDWARE = Use sound card.
Leave on AUTO unless issues arise.

GARAGE TOOL EFFECTS
3D = Play wrench, spray and decal effects from in-world click location.

INPUT FILTERING & FORCE FEEDBACK
-> STEERING HELP
Messes with your steering, in attempt to be helpful. Try driving without it first!
Driving without it is much more natural - if you think you need this, reconsider your choice and front-rear balance of tyres, shocks, springs and sways!

-> EMULATED FFB STRENGTH
Allows FFB system to mess with your steering, even when not using an FFB wheel.

INPUT FILTERS:
Tip: Use TEST AXIS (lower right corner) to check filter effects live!

-> Non-linearity: Input curve.
Increase to reduce input sensitivity near center/zero.
Affects digital inputs too, adding on-center/near-zero 'weight'.
Intended to make smooth driving easier.

Digital input only:
-> Reset rate: How quickly input goes back to zero after releasing key.
-> Rate up: How quickly input goes up upon pressing key.
-> Rate back: How quickly steering goes back to center when inputting a direction opposite of current steering.

CAMERA CONTROLS -> LOCK DRIVING MOUSELOOK
Disables looking around with the mouse when driving in first person mode.
First person view snaps to center upon taking control of the car.
Intended for those using mouse steering.

INVENTORY PANELS
QUADRUPLE = Each inventory slot becomes four smaller slots. Total slot count depends on aspect ratio (7 -> 28 on widescreen, 5 -> 20 on 4:3, etc...).

GARAGE: HIDE SIDE PANEL
Allow garage side panel auto-hide.
Disable if you don't like pressing Esc, and don't have a mouse with any side buttons (see REDEFINE GAME CONTROLS -> ALT ESCAPE bind).

GARAGE: INFOLINE AT CURSOR
Place part name & condition text dynamically next to the cursor, rather than in the lower right corner.

CAR INFO HIGHLIGHTS
Color-code spec changes in Car Info?

SHOW NAVIGATOR
ALWAYS = Normal Nav mode.
CITY ONLY = Don't show Nav on Test Track (it's easy to learn anyway :)).
CITY - AUTO = Show Nav only in the city, and only when needed (Racer/shop marked, during races.)
PEDESTRIAN DIRECTIONS ONLY = Same as above, but without Nav during races, akin to the PRONAV Career mutator.

Running without Nav can improve framerate by ~5%.

DAMAGE INDICATOR
You can disable the damage indicator shown while driving (you'll still see part health in Garage, don't worry :D).
Not knowing can lead to interesting situations :)

N2O AS PERCENTAGE
Show remaining N2O as a percentage inside the navigator, like in the original game.


TACH: HIDE IN FIRST PERSON
Enable this for added immersion when driving in first person view.
Warning: In-car gauges can be less accurate, sometimes significantly!

TACH: KANADIAN MILES
Metric speed (KM).

TACH: DIGITAL FONT
Disable to use the original SL1 font for speed & gear display.


PEDESTRIAN BLABBER
ALLOW PROFANITY = Show all pedestrian responses submitted by SL1R crowdfunding supporters.
HIDE PROFANITY = Hide/lightly modify responses with profanity.
CLASSIC LINES ONLY = "What do YOU want?".

RACER RANGEFINDER
Show the 'two cars' icon whenever near a cruising opponent. Check for (lack of) this icon before honking at a pedestrian, to know if you're far enough away for him to mark a new racer.
If you'd rather go by feel, like you had to in the original game, you can disable this.

UNIQUE ENVMAPS
SL1R features new ENVironment maps (AKA reflection maps) for more realistic car & part appearance in garages & CarLot.
You can disable them, to bring back the original game's colder feel.

ON vs. OFF:
Though they appear to reflect the local environment, these are NOT realtime reflections, and do not affect performance! This is purely about visual preference :)

GARAGE: CLEAN AIR
Disables subtle interior fogging (also applies to shops & carlot).

CARLOT CAR LOAD WIDTH
Defines how the CarLot loads cars;

NARROW: Old loading mode - one car is loaded on each side of your current selection.
AUTO: The old mode was designed for 4:3 aspect ratio - wider aspect ratios meant you could see blank spots on each side. In this AUTO mode, additional cars are loaded depending on your aspect ratio, to avoid this problem.
AUTO + PRELOAD 2: AUTO mode, with enabled pre-loading - default!
Pre-loading increases how many cars are loaded at a time, so though loading duration increases, you won't get a stutter every time you change selection!
WHOLE LEVEL: Loads the entire selected level, to completely eliminate stutters when selecting cars side-to-side, at the expense of slower entry & level changes.

AUTO-INSTALL REPAIRED PARTS
After you repair a part, it will instantly be auto-installed to your car, saving the additional click.
You can INVERT the behavior anytime by holding Shift as you confirm repair;

If you hold Shift:
Option disabled -> WILL auto-install;
Option enabled -> WON'T auto-install.

By using the Repair hotkey in combination with the Enter key, you can very quickly reassemble + repair all parts of your car without ever touching the mouse :)

PAINT SURFACE RESOLUTION
The quality of paint, scratches and decals on part surfaces.
Cars & parts are generated with very low resolution paint, to improve load times;
Upon purchase, parts are automatically upgraded to an appropriate resolution, depending on their size.
Increasing this will notably increase load times, and depending on your GPU, may introduce stutters when painting or when parts get scratched from impacts.
HIGH will increase paint resolution of most parts. Chassis resolution goes from 512x512 to 1024x1024.
ULTRA will allow 1024x1024 resolution to be used for large bodyparts, not just the chassis.
As you can see, some cars do not feature body parts large enough to necessitate max resolution, even at ULTRA.
For reference, SL1 originally used 256x256 for all parts, including chassis.
SLRR 2.3.1 uses 1024x1024.

CATALOG: MATCH FACTORY COLOR
Bodywork offered in the Catalog will match your car's factory color (listed in CarInfo).

GHOST DRIVERS
Hide driver model inside player, opponent & police cars.

WALK SPEED
First person walk speed in meters per second. Set to max to allow reaching run speed without holding Shift.

LOADING STATUS TEXT
Display what the game is doing during loading screens in the lower right corner.
Can be helpful for diagnosing game crashes.

LOADING SCREENS
AGGRESSIVE = Hide loading screens quicker, even if nearby scenery hasn't fully loaded yet.
OFF = Disable loading screens entirely.

SPLASH SCREEN
OFF = Auto-skip splash screen for faster startup, but fewer pre-cached resources.