Quote:
Originally Posted by midwest x6
What am I missing to draw an accurate conclusion?  |
1) 1st question is what will happen to fuel prices in the medium term. Assume your figures are right for now, but it is more likely that diesel will rise more quickly than gasoline, due to refinery capacity. That isn't for sure, but it is widely forecast. Suggest you don't worry about it for now, as nobody knows for sure.
2) 2nd question is whether those are actual mileage figures. If you owned both vehicles, and measured over full tanks as opposed to relying on the on board computer readout, then you likely have better data than having to rely on government fuel consumption figures.
3) 3rd question is whether that is summer or winter diesel. Winter diesel will usually produce lower mpg due to lower energy content than summer diesel.
4) Once all the above is qualified, then all you are missing is the formula. Fuel prices and mileage figures as you have shown them are hard to combine together, what you need to calculate is the $/mile. Using your figures, the diesel is costing $0.18 per mile, and the gasoline model is costing $0.26 per mile. Assume the same maintenance costs. Savings of $0.08 per mile equate to a 32% improvement, and will allow you to calculate a payback period (in miles) based on how much it cost you to move to the diesel, if anything. ie, for every $1000 of cost (purchase price, taxes, etc) you will have to drive just over 12,000 miles to break even. OTOH, if the diesel was cheaper, you are already ahead.