Surely, it's how much fuel a person uses in total which determines
his/her 'transport' contribution to greenhouse gas emissions, not the
efficiency of one of the vehicles he may use?

I try not to use any. My system is hibernated every night - and I
don't drive. I recycle as much as I possibly can (I would do more but
our local council doesn't take high-density polyurethane (HDPE) which
is what the tops of the milk 'tanks' you can buy in most supermarkets
are made from). I refill my ink cartridges, and I never print unless
it's absolutely necessary, then the results, if not used, are turned
into phone pads.

You must save quite a lot of money doing these things. What do you spend the
money on that you saved? It's highly likely that you spend it on things or
services that consume resources.

Ultimately, to make a real difference, there simply needs to be less of us
on this planet.

Though I'm not planning to leave anytime soon myself...

Regards

Martin