The short answer is yes. A well-serviced car runs more efficiently than a neglected one, and the difference shows up at the fuel pump. Clean air filters, fresh oil, correctly inflated tyres, properly gapped spark plugs, and a healthy engine all reduce the amount of fuel needed to cover the same distance.
We're putting together the full guide now, covering exactly which service items affect mpg, by how much, and how to spot the early signs that your fuel economy is slipping because of overdue maintenance.
In the meantime, here are the related guides you may find useful: