My car is at the garage being repaired by the other driver's insurance company. Am I entitled to be compensated for the loss of the use of my car, even though I don't need to rent another car?
Yes. The law provides that you are entitled to compensation for loss of the use of your vehicle while it is being repaired. This is the reasonable rental value of a substitute car.
You do not have to rent a replacement car or actually spend money for alternative transportation to be entitled to compensation for the loss of the use of your car.