Once you have your car's fuel efficiency, you can calculate the approximate amount of petrol you will need using the following formula:
```
Fuel consumption (gallons or litres) = Distance (miles or kilometres) / Fuel efficiency (mpg or km/L)
```
For example, if your car has a fuel efficiency of 40 mpg and you are driving 440 miles, your fuel consumption would be:
```
Fuel consumption (gallons) = 440 miles / 40 mpg = 11 gallons
```
Therefore, you would use approximately 11 gallons of petrol to drive 440 miles with a car that has a fuel efficiency of 40 mpg.
It's important to note that this calculation is an estimate, and the actual fuel consumption may vary depending on factors such as traffic conditions, driving style, road conditions, and vehicle load.