Petroleum Conservation Research Association (PCRA) is the agency which advises people how to save petrol/diesel while driving vehicles.

Answer

**Step-by-Step Text Solution:**

1. **Understanding PCRA**: The Petroleum Conservation Research Association (PCRA) is an organization that provides guidance on how to conserve fuel, specifically petrol and diesel, while driving vehicles.

2. **True Statement**: The statement given in the question is true. PCRA indeed advises people on fuel conservation techniques.

3. **Tips for Fuel Conservation**:
- **Tip 1**: Drive at a constant and moderate speed. This helps in maintaining fuel efficiency and reduces unnecessary fuel consumption.
- **Tip 2**: Switch off the engine when at traffic signals or when waiting for extended periods. This prevents fuel wastage while the vehicle is idle.

4. **Conclusion**: By following the advice provided by PCRA, such as driving at a constant speed and turning off the engine when not in motion, individuals can effectively save petrol and diesel.

---