on petrol consumption .... haven't got any current figures but twin su's when driven sensibly are good on fuel, give 'em a hard time and the fuel guage will let you know
as for twin 40's the same thing goes but they will use more than su's in just cruising around.
on an old engine (A14) lots of work and big cam i was getting atleast 450+km's with twin 40 dellortos. this was in a 1000 2door, which involved roughly 50% highway and 50% town driving