Yes, roly, CAM often makes the astute observation sound simple. I have taken your advice and thought again about the world's transport systems but gave up. Last year I went to a talk on alternative transport given by a green guru from the local uni and attended by a small army of vegans and SJWs all smelling of patchouli oil. Oddly the vast majority arrived in cars but I was too polite to point this out. I did suggest to one friend who is very big on the environment that he might get rid of his 4x4 but he looked aghast and told me it was essential for towing his boat. No, my friend, we are well and truly knackered.