Trip Computer Range Vs. Petrol Gauge

[petem]

Hi everyone, I'm delighted to find this board.

I have one burning question:

Which is likely to be the more accurate, my Avensis estate's onboard trip computer that tells me how far I can go with my current fuel, or the petrol gauge? The yellow warning light often comes on and the needle points to empty even when the computer tells me that I have a range of 40-60 miles.

Which should I trust?

Thanks

Pete