In the Australian state of New South Wales, 3 seconds of following distance is recommended.
[1] In Queensland,[2] Victoria,[3] and Western Australia,[4] 2 seconds is recommended.
[5] In the UK, it is recommended that 2 seconds of following distance is maintained.
[6] In the US, for safety it is recommended that 3-4 seconds of following distance is maintained.
[7] Extra time should be added for wet, rainy, slippery, foggy or other weather situations accordingly.