One of the main reasons for that is that it's an awful lot slower. I live about 40 miles from work at the moment, which I cover in about 50 minutes door-to-door

One of the main reasons for that is that it's an awful lot slower. I live about 40 miles from work at the moment, which I cover in about 50 minutes door-to-door; there is absolutely no way I could achieve that on a bike. I'd guess that might take me 3-4 hours each way, so hence the bike is unfortunately not an option, regardless of its energy efficiency or cost.