My current method of measuring mileage per tank is in my Cavalier that's driven daily and a family car(racking up more than 3000 miles per month, every month). Being given to our daughter in a month. I've also used this method on my 97 Suburban 4x4, and the family van being a Merc. villager. Works without question.
The donor is a Toyota corolla 92 model 1.8 FI auto 4 dr. so the back seats going by-by. It has a distributor to help with adjustments. In tank pump which is a bonus. Injectors also help my plans. This was a customers car that his wife wrecked and i repaired, however he bought another car during the process and we made a deal for the car to be an experimental project. So long as i could return it to its original state some day. NO PROBLEM'O !!!!!
Its done right or its not done !
Hail HHO.