Am I calculating this correctly? (v-8/v-10/diesel)

[dave_in_delaware]

Disclaimer: No, I don't mean for this to be a "battle thread" for gas vs diesel!!! I just want to make sure I'm going about this "logic" correctly.

I have been curious about the differences between all the engine options for the Ford vans in the following categories:

- mpg
- fill-up cost
- range on one tank
- travel "unit" costs

So I typed up a little Excel chart and plugged some numbers in, using:

gas v-8 gets 15 mpg, 35 gal fuel tank
gas v-10 gets 12 mpg, 35 gal fuel tank
diesel v-8 gets 18 mpg, 35 gal fuel tank
(these stats come from SMB's website)

Current "cheap" gas prices are:

regular = $2.56/gal
diesel = $3.59/gal
(local gas prices came from gasbuddy.com)

So, in figuring out something like the fill-up cost, I'd take the tank size and multiply by the price:

[gal] x [$/gal] = total $ fill-up cost

so, the gassers would cost about $90 to fill up, vs $126 for the diesel. That could be a significant difference....

Then, to calculate the range I'd get out of a full tank of gas, I'd take the mpg and multiply by the tank size:

mpg x tank size = range

gas v-8 could go 525 miles
gas v-10 could go 420 miles
diesel v-8 could go 630 miles

Wow! Big difference between the v-10 gasser and a diesel!

And then, just out of curiosity, I wondered how the three compared to each other in terms of cost/mile, so I divided the fill-up cost by range:

fill-up cost/range = $/mile

gas v-8 is $0.170667/mile
gas v-10 is $0.213333/mile
diesel v-8 is $0.199444/mile

Which, to me, shows that there's not much difference between the three options. Actually, the biggest difference would be 4¢/mile! No big deal.

Granted, I didn't take into account initial up-front cost differences, maintenance, break-downs, repairs, etc, nor did I take into account depreciation, resale value, etc...

But, is my logic correct? Is the "end" result showing not much difference between $/mile costs using reasonable logic?

Again, this isn't a gas vs diesel war thread, just a more straight-up comparison idea.

Thoughts? Concerns? Am I totally off my rocker?

[Ford_6L_E350]

Everything looks good.

Except, I bought diesel in CA for $3.29 over the weekend. Regular seems to be about the same price ($3.29) around here.

And you do need to look at the much higher maintainance costs for the diesel. Fuel filters ($45) every 15K, oil filters ($25), air filters ($50), 14 Quarts of oil every change.

Also, very few diesel owners actually get 18mpg. From all the reports I've seen, 15mpg might be more realistic.

Mike

[dave_in_delaware]

Thanks, Mike.

Well, yeah, I'm sure fuel prices will vary GREATLY depending on your area. They're definitely NOT the same price around here.

And the mpg numbers I got from SMB's website, although I do recall mpg numbers in many posts closer to what you've indicated.

From what I've read on this forum, maintenance on a diesel seems to be much higher than a gas engine. I didn't take any maintenance into account.

I guess the overall "statistic" I was looking at was sort of a "price per mile for a vacation" travel idea. Which, seems to be the same between the three options IF the fuel prices aren't the same.

[jage]

Your calculations look correct, although it is easier to just take the price of a gallon and divide by mpg:

$3.95/14.6m ("per gallons" cancel out) = 27.05¢/mile approximately what mine costs to drive around on the current tank.

Even so a ¢ per mile is hardly a true representation of ownership costs- and as you noted hardly a decisive number. If you really want to save on fuel costs you should be looking at Sprinters.

[dave_in_delaware]

My calulations were all laid out in an Excel file, doing the calcs for me. I had each stat in a column, and just ran some numbers, not trying to come to the conclusion the fastest.

You're right, though: Sprinters get the best gas mileage.

But I've seen some of them around here. They're too friggin' big for my tastes, so I didn't include those in my calcs. (If I wanted to drive a giant box around, I'd work for FedEx).

[wannaSMB]

Our dual tank set-up has capacity for 56 gallons (at the pump, my debit card usually gets cut off before I'm full). In theory then, I can go 900 miles between fill-ups (I'm getting 16mpg).

Assuming I can get a home equity loan to pay for the fuel, of course.

[Greg In Austin]

I think I agree with Jage, make it simple.

because....

Our diesel tank is 46 gallons.

...and although it takes 16 qts of oil to fill, my recent research tells me that we will NEVER again change that entire volume. From this point (9k miles) only be changing the filters every 12k miles and topping off the oil we lose during that operation.

...and then you probably need to work in the life expectancy and associated costs....

[BroncoHauler]

Another non-quantitative factor to consider is if you plan on towing anything heavy. I'm sure people will point out exceptions, but I think the gasser V8 is underpowered for significant towing, especially if it's in any mountains.

Just trying to narrow down your options so you don't over analyze things.

I will also agree with Mike that most people seem to get in the area of 15 mpg rather than 18 for the diesel. As for diesel prices, they are now near if not the same as regular gas, but I'm not sure that will last. It's been years since I've seen that, though I do remember way back when diesel was cheaper than regular.


Herb

[dave_in_delaware]

Diesel and gas prices around here are not even close....

[jage]

Mmmm, I remember having to buy Lead additive for every tank with my Comet GT.

I'm sure some of you remember when unleaded gas was introduced... tires were a nickle and we all walked miles to school, uphill, both ways. Sigh, the good old days.