No, I'm not talking about driving, drinking or other ages! How many gallons does our tank hold? The spec. says the capacity is 18.5 gallons, and that there is a 2.5 gal. reserve. Does the 2.5 come out of the 18.5 or is it in addition to the 18.5 (hence, the 21)? It seems I put in about 15 gals. when the fuel gauge needle is at 1/4, so I'm thinking that the 2.5 is in addition for a total of 21. Doesn't the light come on when you're at "E" and then have 2.5 left? Of course, maybe my calibration is off. Also, every magazine article I've read on the M5 puts the fuel capacity at 18.5, but I'm wondering if they just didn't count the reserve either?