Two year Fuel Economy Update

I have finally managed to crunch all the numbers for year two’s fuel economy, as well as the two year average. This year, we drove our Suburban 21,498 miles (as of June 30, 2012). The Suburban consumed 888.972 gallons of diesel fuel, for an average of 24.183 MPG for year two. Over the life of the conversion, we have driven 39,983 miles, consumed 1629.830 Gallons of fuel, for a two year average of 24.532 MPG. I have also figured out that if we drove it just as far, but it was gas, getting about 16 MPG average, then we would have used 2499 gallons of gas. At $3.459 per gallon, we would have spent $8644.05 on gas. Instead, we burned 1629 gallons of diesel, at 3.909 per gallon, we spent $6367.76 on diesel fuel, for a total savings of $2276.29, which is nearly the entire cost of the Suburban (which I bought with a bad engine and trans) plus the diesel conversion. A fresh gas engine and trans wouldn’t have been much cheaper, so I think I made out pretty good!

Awesome numbers. Yea, I think you came out OK.

Guess it goes to show that the old adage of "you'll never get the money back out of a conversion" isn't so true...

It depends: Had this Suburban had a good engine and transmission to begin with, it might not have, or the payoff would have been 4-5 years down the road. Also, had I not scoured the U-Pull yards for parts and bought a rusted out 84 Suburban for 300.00 for parts, it probably would have been cost prohibitive as well. In fact, to be honest, I had an engine before I had a Suburban to put it in. Doing a conversion was the plan from the start, so I looked for a Suburban with a tired drivetrain to begin with. Also, I can not over emphasize the importance of planning the project out, doing the research, and having everything all laid out before turning the first wrench. It took me 2 years to accumulate the parts and materials I needed and complete the job, and even then, with a solid plan, there were still snags that required money. I think that a lot of conversions don't wash because of poor planning or underestimating the magnitude of the job, or impatience to get it done (thus buying expensive parts instead of wrenching at the U-pull). Finally, I was willing to live with Chevy 305 Horsepower and build for maximum economy, instead of trying to make it faster than the gas 350 it replaced, which would have made the project much more expensive.