Definitely! You can find the Extend button in the app under your ongoing booking. Tap on it and extend the booking duration to your desired time.
You will be able to extend in 15 minutes time slots as well. Do make sure to extend early if you know that you will require to use the car for a longer period of time. Please also do make sure that you have confirmed your extension which should reflect on your app. The extension will not be confirmed if there is already someone else who is using the vehicle after you.
Do note that extension is subjected to the availability of the car.