This page aims to document all upgrades to cars in GTA 5 that have a tangible impact on performance and should be used by every player. This video is also an option for a more simplified explanation with visual aids.
Written by: Broughy1322
These apply to all cars that have them and should be upgraded to the maximum level possible.
Not all cars in GTA have a spoiler modification, but those that do will receive an increase in grip when any non-stock spoiler option is chosen, resulting in higher cornering speeds. To clarify, “non-stock” means any spoiler that isn’t the top option in the spoilers category list. All spoilers below the option at the top of the list will give the same increase in grip - larger spoilers aren’t any better than smaller spoilers in this respect. Some cars like the T20 and Furia have active spoilers which give the increase in grip by default, however if they are broken mid-race the car will experience grip loss until fixed as shown here. Spoilers also have no effect on top speed as shown here.
Some high performance cars have a downforce multiplier. The higher the car’s downforce value, the better cornering ability it has when travelling at high speed. After many changes by Rockstar over the years, spoilers are now required for these cars and will still improve cornering speeds, but to a lesser extent than if they were added to a non-downforce car. For more background on the difference between downforce and spoilers, see here.
For cars that don’t have a spoiler category in Los Santos Customs, it’s possible that they receive an increase in grip from other modifications. Keep an eye out for the traction bar increasing when upgrading to identify these parts, or look for the "Adds traction like a spoiler" category in the performance section of the vehicle's page on this site (like with the Dubsta for example).
Any car that came before the Casino DLC that has the “Tyres Can Clip” flag in the handling data will be smoother over kerbs and bumps in the road when they have off-road wheels applied, making them much more stable. A lesser benefit will be experienced with other wheels depending on the size of the tyre sidewall. Because off-road wheels have the biggest sidewall, they give the biggest benefit. More details here.
You can find which cars benefit from this by checking to see if the vehicle has the "Better with off-roads" improvement in the performance section of a vehicle's page on this site (like with the Osiris for example). For these cars any wheel from the Off-Road category will improve bump absorption, with wheels from the Tuner and Muscle category also helping but to a lesser extent. Some of these cars do however get a bigger kerb boost from wheels with less sidewall, such as High Ends, while sacrificing stability.
In general suspension options don’t impact car performance. A car will be no quicker or slower by running the lowest suspension vs the highest for example. However a small number of cars introduced from 2019 onward have a handling flag which actually increases the amount of traction they have when lower suspension is applied (most notably cars in the Tuners class, but also things like the Asbo).
You can find which cars benefit from this by checking to see if the vehicle has the "Quicker with lowest suspension" improvement in the performance section of a vehice's page on this site (like with the Vectre for example). For these cars the lowest suspension upgrade is the best option and often that involves having cars with extreme negative camber, where the bottom of the wheels tilt outwards. Any car that has suspension induced camber but doesn't have the aforementioned attribute will either handle worse with it or it has a negligible effect.
A small number of cars have a variety of extra boosts. Open Wheel cars have KERS, which regenerates slowly when off the throttle and quickly when braking. Arena vehicles like the ZR380 can have nitrous boost upgrades and special vehicles like the Scramjet have rocket boosts by default. All boosts are most effective when activated at low speed and are fully depleted.
All armour upgrades have zero impact on performance in terms of vehicle speed, but will help with avoiding damage. 100% armour is the best option as it will offer the most protection when your car is involved in crashes and collisions. A damaged car will impact performance negatively and make you slower, so it’s a good idea to protect against it as much as possible.
All other modification options not otherwise mentioned here (such as bumpers, sides skirts, etc), have no tangible impact on performance. Carbon parts aren’t lighter, and other body modifications don’t add grip like spoilers do.
However almost every GTA car modification has a very nuanced and almost imperceptible impact on the way a car feels by changing where the car’s centre of mass is located. The vast majority of people won’t be able to notice this aspect and is something that’s only really applicable to the quickest racers to finely tune the way their cars behave.
While these changes won’t improve the outright speed of a certain car, they can be used to good effect to allow drivers to make cars drive closer to how they prefer, enabling the theoretical maximum of the car to be achieved more consistently. All of this falls under car setups and more information can be read on this page.
With the Tuners update in summer 2021, 17 cars were introduced that had the ability to apply Low Grip tyres at the Los Santos Car Meet. Applying these tyres make cars have much less traction and therefore improve their drifting ability. They will always be slower for lap time and racing, however they have the extra effect of drastically increasing top speed. Setting the vehicle stance in the interaction menu to “Lowered” will further improve top speed, again at the expense of handling.
The top speed testing video, linked here, gives more detail on this towards the end. However, the top speed benefits of doing this were drastically reduced in the following update as Tuner cars were generally nerfed across the board to "fix" this issue, as detailed here.
Open Wheel cars in GTA have high levels of downforce (explained above) but don’t get the usual benefit from spoilers in the traditional sense. Instead, the front and rear wing upgrades actively change the downforce values on the cars. This means that it’s possible to set up all open wheels cars to have high or low levels of downforce.
Naturally there are a huge number of options in this regard, with each front and rear wing modification increasing or decreasing the downforce value of the car by different amounts. This can result in the same cars performing very differently with different mods applied.
You can find the exact effect of every front and rear wing option for every Open Wheel car by checking the Open Wheel Wings section of the main spreadsheet, linked here. In general the further down the list you go the more downforce is applied, but there are exceptions.