If you're wondering how to tow a car without a tow bar, you can use a rope or chain, though as the RAC notes, the distance between the cars can't exceed 4.5 metres. If the distance is greater than 1.5 metres, the rope or chain must be made clearly visible to road users from both sides - for instance, by tying a bright piece of fabric around the middle.
The best way to tow a car is to use a specific tow strap, which has hooks on both ends that easily attach to both cars' towing hitches. If you're using chains, it's possible for the links to stretch and break under the strain.