Is it possible to have a single clip in the timeline going fast speed at the start, slowing down in the middle and then getting fast again at the end. In my case, a car coming towards the camera fast- slowing it right down as you pan round and it goes by- and then speeding away from the camera.
I don't quite get the speed changes in FCP- can someone help?
Yes, but the "variable speed" keyframes can be confusing and hard to work with when doing variable speed changes.
Another way you can try is to lay the clip on the timeline, set the initial speed you want (say 200%), razor blade the clip where you want to change speeds then adjust your speed on the second clip (to say 50%) then razor blade again where you want the speed to change again and adjust the 3rd clip back (to say 200%). Do it in just this order and DO NOT "roll the edit" after you make the speed changes or you will bugger it up.
You wont get those nice "variable speed ramps" you sometimes see out there but you usually want to do this sort of thing to music timing or a sound FX so it works nicely when it is all timed out well.