Hi Krish,
Welcome to the Community. It's essential to correctly record your transactions to keep your books balanced. QuickBooks Online is a great program that gives you the ability to easily track your sales and expenses. I'd be glad to help.
At this time, the program doesn't offer the ability to connect fleet cards. QuickBooks Online offers the option to connect bank accounts and manage imported transactions. You can find your bank or credit card account when you connect to online banking. I encourage you to find a third-party app to complete the task you're looking for. You can click on the Apps tab on the left navigation menu >and then select Find Apps.
If you'd like to include the ability to connect fleet cards to QuickBooks, I recommend that you send us Feedback by clicking on the Gear icon at the top. This is sent to our Development Team to consider for future updates.
Let me know if you have questions, I'll be happy to help.
