This is the 683rd most frequent Greek word.
ταχύτητα
Speed.
The word 'ταχύτητα' refers to the speed or velocity of the mentioned car, used in a noun form to indicate a physical property.
Η ταχύτητα του αυτοκινήτου είναι πολύ μεγάλη.
The speed of the car is very high.
'Ταχύτητα' here again serves as a noun, indicating the pace or quickness of the person in the race, with emphasis on its manipulative aspect.
Πρέπει να αυξήσεις την ταχύτητά σου στον αγώνα.
You need to increase your speed in the race.
In this sentence, 'ταχύτητα' is used to describe the rate of reading, a metaphorical application of speed to an abstract activity.