I think it comes on with three gallons left.

 

On the highway,mine came on with about 2 gallons left.

 

According to the manual the fuel light comes on with 1/8th of gas left in the tank. So since 1/8th is 0.125, it's 19.5 (gallon tank) x 0.125 = about 2.4 gallons left when the light comes on. So, depending on your driving habits, you should be able to calculate miles left from there.

 

Thanks guys!

 

I never drive more than 20 highway miles after the light comes on.

 

my needle was right above (no black in between the red empty bar and needle itself) the red E bar and i put in 17.9 gals. falls right in line with what everyone else is saying above.

 

Whenever mine comes on I set the tripometer just to remind me. I typically figure about 30 miles max, but 20-25 probably should be a safe bet.