Fuel Calculator Overlay

This guide explains how to set up RaceLab with rFactor 2 so you get accurate fuel usage and race fuel predictions. We’ll go step-by-step so you can follow along even if you’re not very technical.  

Tips

• Try to record laps at normal race pace (not slow in-laps or heavy traffic).
• If conditions change (rain, damage, draft), keep an eye on the values and adjust if needed.
• In endurance or team races, make sure all drivers understand which setting is used in the calculator.

If the Fuel Calculator gives strange numbers, check that the correct session length, car and fuel tank size are selected in the Racelab app, and make sure you have logged enough valid laps.

By the end, RaceLab will show you:

• Average fuel used per lap
• How many laps of fuel you have left
• How much fuel to add for a race or stint
• A safety margin so you don’t run out on the last lap

1. How RaceLab Calculates Fuel in rFactor 2

RaceLab connects to rFactor 2 and reads live telemetry (fuel level, laps completed, lap times, etc.). From this, it calculates:

• Fuel per lap – based on how much fuel you actually used over several clean laps.
• Total fuel needed – fuel per lap × laps remaining + your safety margin.
• Fuel to add – how much extra fuel you should put in the car at your next pit stop.

For timed races (for example, a 30-minute race), RaceLab estimates how many laps you’ll do using your average lap time and then works out the fuel needed for that number of laps.

2. Step-by-Step Setup – rFactor 2 & Telemetry

Follow these steps to make sure rFactor 2 is sending the information RaceLab needs.

Step 1 – Close rFactor 2

Before editing any files, make sure rFactor 2 is closed.

Step 2 – Open the rFactor 2 UserData Folder

Browse to your rFactor 2 installation. The default path is usually similar to:

Steam\steamapps\common\rFactor 2\UserData\player\

In this folder, look for a file called: CustomPluginVariables.JSON

Step 3 – Enable the Internals Plugin

Open CustomPluginVariables.JSON with a text editor such as Notepad.

Find the section that mentions InternalsPlugin.dll. It will look similar to this:

"InternalsPlugin.dll":{
" Enabled":1
}

• If " Enabled" is 0, change it to 1.
• Save the file and close the editor.

Step 4 – (Optional) Check Broadcasting / UDP Settings

Some setups use rFactor 2’s broadcasting options. In newer builds, you may see a section like:

"Broadcasting":{
" Enabled":true,
" Port":8188
}

If you see a broadcasting section and it is disabled, you can set:

• " Enabled":true
• Leave the Port at the default unless you have a special reason to change it.

3. Step-by-Step Setup – RaceLab Side

Step 1 – Start rFactor 2 First

Start rFactor 2 and load into the track with the car and session you want to use.

Step 2 – Launch RaceLab

Open the RaceLab App on your PC. Once rFactor 2 is running, RaceLab should automatically detect it and show the sim name at the top of the app window.

Step 3 – Enable the Fuel Overlay

1. In RaceLab, open the Overlay Manager.
2. Find the widget called something like Fuel, Fuel & Stint, or Race Info.
3. Enable the widget and position it where you want on screen.
4. Click Save or Apply to confirm the overlay layout.

Step 4 – Drive a Few Laps

Now hop on track and drive:

• At least 3–5 clean laps at your normal race pace.
• Avoid pitting or resetting the car during these first laps if possible.

As you complete laps, RaceLab will:

• Detect your fuel per lap
• Estimate laps remaining with current fuel
• Show how much fuel you’ll need to finish the session or race

4. Understanding the Numbers on the Fuel Overlay

Different RaceLab layouts may show slightly different labels, but generally you will see:

• Fuel / Lap – your current average fuel usage per lap (usually in litres).
• Laps Left – how many laps you can complete with the fuel currently in the tank.
• Fuel Needed – total fuel required to finish the race or session.
• Fuel to Add – how much extra fuel you need to add at your next stop.

Example Calculation

Imagine this situation:

• After 5 laps, you have used 7.5 L of fuel.
• Average = 1.5 L per lap.
• The race distance is 20 laps.
• You currently have 10 L in the tank.
• You want a safety margin of 1 extra lap.

The calculation looks like this:

Fuel needed = (1.5 L × 20 laps) + 1.5 L (1 extra lap)
= 30 L + 1.5 L
= 31.5 L total
Fuel to add = 31.5 L - 10 L (currently in tank)
= 21.5 L

RaceLab will show something similar to: Fuel needed: 31.5 L, Add: 21.5 L.

5. Recommended Safety Margin

To avoid running out of fuel because of traffic, mistakes, or safety cars, it’s smart to add a little extra. Common options:

• +1 extra lap of fuel
• +5–10% extra on top of the calculated amount

Pick whichever style you find easier. The important thing is to always allow a small buffer.

6. Common Problems & Fixes

7. Quick Checklist

• ✅ rFactor 2 closed before editing files
• ✅ CustomPluginVariables.JSON edited and InternalsPlugin.dll enabled
• ✅ Broadcasting / telemetry options enabled if required
• ✅ RaceLab running and rFactor 2 detected
• ✅ Fuel / Race Info overlay enabled and visible
• ✅ 3–5 clean laps driven at normal pace
• ✅ Safety margin set (extra lap or percentage)

If you’re still having trouble with rFactor 2 fuel calculations in RaceLab, feel free to contact me on Discord – I’m SCOTTOZY on the official RaceLab.app server and I’ll do my best to help.