Acceleration in GTA San Andreas Handling
A lot has changed since GTA 3 and GTA Vice City. We have much more control over how a vehicle accelerates in the GTA San Andreas handling.cfg.
Settings Which Affect Acceleration
There are several relevant values in the.
| Effect on Acceleration | Effect on Top Speed | |
|---|---|---|
Mass
| Higher value slows acceleration. | No change (different to earlier editions). |
Drag
| Higher value slows acceleration. | Higher value reduces top speed. |
Acceleration
| Higher value increases acceleration. | Higher value increases top speed up to the TopSpeed limit.
|
Inertia
| Higher value slows acceleration. | No change. |
TopSpeed
| No change. | Limits the top speed. Details are below. |
Actions Which Affect Acceleration
| Action | Effect on Acceleration |
|---|---|
| Driving up a slope. | Decreases. |
| Driving down a slope. | Increases. |
| Leaning forward slightly on a motorbike or quadbike. | Increases. |
| Retracting landing gear of planes. | Increases. |
| Nitro Boost | Increases. |
Recipe for Realistic Acceleration
Real sports cars take 5 to 10 seconds to reach 100km/h, about 30 seconds to reach 200km/h and 1 or 2 minutes to reach maximum speed.
This is much slower than original GTA San Andreas setups but after a while it will feel a bit like Gran Turismo. My GTA San Andreas Handling Overhaul has some realistic setups for the original cars.
Mass
The real world mass of the vehicle in kilogrammes. Normally between 1000 and 2000.
Drag
This should be much lower than original setups. As a rough guide:
| Value | Type of Vehicle |
|---|---|
0.8
| Streamlined supercar. |
1.0
| Normal saloon (sedan). |
1.3
| Open top cars. |
TopSpeed
Should be the maximum possible speed which can be achieved in the highest gear in kilometers per hour. This will normally be higher than the speed the vehicle can reach on a flat road without using nitro boost.
The TopSpeed setting has 2 modes. The mode is selected by USE_MAXSP_LIMIT, which is the 25th bit of the HandlingFlags setting.
USE_MAXSP_LIMIT
| Acceleration Mode | Notes |
|---|---|---|
| 0 | Normal | Maximum speed is about 20% higher than TopSpeed value.
|
| 1 | Advanced | Maximum speed is the same as TopSpeed value.
|
A vehicle might not be powerful enough to reach the TopSpeed limit. Changing TopSpeed does not change Acceleration or Drag.
Acceleration
Sets the normal rate of acceleration. As a rough guide:
| Value | Type of Vehicle |
|---|---|
15
| Normal car |
25
| Sports car |
30
| Very powerful supercar |
Inertia
This is the key to realistic acceleration. A high value smooths out the acceleration curve. A value between 80 and 120 is good for most vehicles.
HandlingFlags
The USE_MAXSPD_LIMIT entry for the HandlingFlags setting should be enabled by being ticked in my CFG Studio Handling Editor. This makes TopSpeed a precise limit.
Special Vehicles
Flying vehicles (planes) and floating vehicles (boats) have special data in sections at the end of the handling.cfg file. They also use a completely different method for their acceleration performance which I don’t understand.
The effect of special data on acceleration is not covered in this tutorial. All settings are briefly described in my GTA San Andreas Handling Definition.
Taxi Experiments
All my experiments are based on completely original Taxi handling, driving the car in a straight line on a flat road (the Julius Thru Way around Las Venturas). The Taxi is the modern one, not the old Cabbie thing.
Original Settings
These are the original values. Using them puts the Taxi back to normal.
TAXI 1450.0 4056.4 2.2 0.0 0.3 -0.25 75 0.80 0.75 0.45 5 180.0 19.0 10.0 F P 9.1 0.60 0 35.0 1.4 0.1 0.0 0.25 -0.15 0.54 0.0 0.2 0.51 20000 0 200000 0 1 0Normal Taxi Acceleration Curve
Now the experiments go from top speed to the way the car accelerates. By comparing this curve of the standard Taxi acceleration to the graphs below, you can see the different effects of different parameters. Note that the standard Taxi has a 0-100km/h time of about five seconds but a top speed of only 144km/h! This is the lack of realism you can expect from the normal acceleration mode.
Effect of Acceleration on Top Speed
More acceleration means a higher top speed, as you would expect. The TopSpeed setting gives an artificial limit to the maximum speed a vehicle can reach.
Effect of Drag on Top Speed
With a value of 0 for Drag, the Taxi should keep getting faster and faster as there would be no resistance. This does not happen because the TopSpeed setting is limiting the top speed, but this is set to only be 180km/h.
Ofer Porat experimented with the original GTA San Andreas cars and published his results. It seems that a car’s speed limit will be 20% higher than the TopSpeed setting when in the normal acceleration mode. In the advanced acceleration mode, the TopSpeed setting limits top speed precisely.
Effect of Inertia on Taxi Acceleration Curve
This seems to be the key value to better acceleration curves. A higher Engine Inertia value will make acceleration more gradual without lowering the top speed. Unfortunately, the limited top speed makes the car suddenly stop accelerating when it should gradually stop accelerating.
Effect of Drag Multiplier on Taxi Acceleration Curve
We have already seen the effect of Drag Multiplier on top speed, so here we see how it effects the way the car accelerates. Basically, a high drag makes the vehicle accelerate more slowly and reach a lower top speed. Interestingly, a low Drag Multiplier means the car takes longer to reach its top speed, which is increased. Another important part of realistic acceleration.
Notes on Top Speed
It is interesting that the vehicle does not always achieve the TopSpeed value of 180km/h, which becomes 214km/h in the game. When the Acceleration is too small relative to the Drag setting, the vehicle will not reach its TopSpeed setting.
This means that the TopSpeed setting is simply a limit to the speed of the vehicle. Your vehicle might never actually reach this speed.