Hello fellow UK ecomodder
I took my time to go through and apply some of the
100+ Hypermiling tips and have massively improved my economy just by the way I drive. Also, first things first, increase your tyre pressures. Ive got mine at the maximum sidewall rating on my tyres (45psi) although some people run a tad lower, some run higher still.
This can make a decent difference
I think a little Micra should be able to crack more than 40, dependent on driving style of course
Good luck