About right
Somewhere in the 4 to 4.5 ltr range sounds about right but it will of course depend on how much taxing you have to do I would think the taxi burn at Biggin Hill on a busy day would be much higher than for your average GA airfield.
As a general rule I use 4 Lts for taxi on my 180 hp Lycoming and just except that any extra burn can come out of the 5% contingency fuel built into the fuel plan.
Generally you only have to look carefully at taxi fuel when you are planning a long flight or your take off fuel is restricted due to the payload.
28 ltr/ hr sounds like a very low fuel burn, what power setting are you basing this on ?
Last edited by A and C; 26th Jan 2013 at 15:40.