How could you determine the instantaneous speed during a

trip?

The moving object has both velocity and speed it shows how fast an object is moved instantaneous speed is the motion rate of an object at particular time period of a moment

Look at your speedometer for say, a couple of seconds. Depends on whether or not you are moving on average at a constant speed (speedo won't change much) or whether you're in a polluting traffic jam/queue in which case the speedo will go up and down like a yo yo. to determine the speed, you'd probably need to plot the speed on the speedo against the times at which the speedo speeds were read from the speedo.