4.2 V8 - Real life fuel economy

[hunker7]

Even though car is fitted with LPG, I think everyone can agree they run better on unleaded. So filled the tank up with premium unleaded just to see what milage I can get out of it.

Just wondering what sorta figures people get out of their V8s? I can't seem to be breaking 25 mpg at any point really, town or motorway.

Seems quite low, D2 4.2 I had previously would do 30 mpg quite easily on motorway, just want to make sure something isn't a miss and she runs as she should.