Hi Dave,

This is the data I have from 24 2300 miles trips I've taken along the same route in the last 12 years. 12 of the trips were heading west, 12 heading east.
55,200 miles and 168 fueling events.

They were all 3 day trips in either an 84, 90, or 91 245 automatic. The average daily run was 766 miles and 15.3 hours driving time.

I filled up as soon as possible after the gauge was in the red, which was consistently around 300 miles on all 3 cars. It's hard to say exactly.

Average miles between fills....327 miles
Average fuel volume at fill... 11.5 US gallons which gives an
Average mileage of ... 28.4 mpg

That mileage gives these cars a theoretical range of 450 miles on a full 15.8 gallon tank. I haven't tried to prove that, but I have done over 400 a few times when a station I'd planned on was closed. It's a little off putting though, because the needle is almost off the scale entirely.

If I'm in the black zone of the gauge for 327 miles and the car's range is 450, then the black zone accounts for 73% of the gas, leaving 27% for the red zone. That's about a quarter tank, a good time to gas up for the health of the pumps, but a fair ways from empty.

I think this concurs with Art's comments above, although it depends on where you travel. I wouldn't suggest heading north up I95 from Bangor, Maine on a snowy night with a quarter tank while thinking you're good for 2 or 3 exits. That is unless hiking's your thing. In most of the country though, I expect you'd be fine.

Peter