Always heard that hirer
complain about their relief makan their fuel.
My Fan (Michael Tan 卖鸡蛋) which is a Sonata CDG Hirer, complain
to me about the same issues.

Give the information to 卖鸡蛋.
There are some workshop can do some magic to the fuel
tank.
(Exactly do what, the workshop woun't tell you, they said there is
their trade secret)
Accroding to Michael, he pay S$40 to the workshop
to do some form of modification to his Sonata Fuel tank.
And after the "Modification", it take him much shorter time to top up
his sonata fuel tank.
And he and his relief agreed every time top up fuel, once the
pump auto stop pumping,
Then just stop pumping.
And then onward, he feel his relief pumped fuel mileage quite
stable liao.
According to some 专家 those
workshop maybe had replace the original fuel tank pressure relief
valve to a lesser pressure vale or 。。。。。。
So, when you top up your fuel, once the pressure build up in the
fuel tank,
very easy will escape through the
"Modify" pressure relief
valve 。。。。。。。