I checked the other question that you asked stating that you were a sub-contractor and drove a vehicle not owned by you to do your deliveries. Based on this question, I am assuming that you bought gasoline for the vehicle from your own funds.
If the gasoline expenses were not reimbursed to you, or if they were reimbursed and included in the income that was reported to you, then yes, you can deduct the expenses for the gasoline as a business expense on your Schedule C.
Do not enter this expense in the vehicle section since that is only for using your own vehicle for business purposes. Instead, you could enter it as a miscellaneous expense using the steps below:
On the top row of the TurboTax online screen, click on Search (or for CD/downloaded TurboTax locate the search box in the upper right corner)
This opens a box where you can type in “schedule c” (be sure to enter exactly as shown here) and click the magnifying glass (or for CD/downloaded TurboTax, click Find)
The search results will give you an option to “Jump to schedule c”
Click on the blue “Jump to schedule c” link
Click Edit beside your business
Scroll to Business Expenses
Click Edit beside Other Common Business Expenses
Scroll to the bottom of the page
Click Start or Update beside Other Miscellaneous Expenses