Author Topic: Gas vs Diesel vs MPG  (Read 290 times)

Offline somewhereinusa

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Gas vs Diesel vs MPG
« on: February 18, 2019, 04:35:02 AM »
On some other board there is always a discussion of gas vs diesel. Thought I'd make a comparison. I also made a comparison for MPG vs fuel cost. Please only change the numbers in the GREEN boxes. Link to google sheets here.   https://docs.google.com/spreadsheets/d/1zSyM7O9YVHSUaADu6jN9rfjQ-v03rMFHx4H-YR8szDQ/edit?usp=sharing

I was a bit surprised at how much you could play with the numbers and diesel came out ahead.  Just for fun, change miles to 100,000 to see what difference  $0.01 vs .1 MPG makes to a long haul truck driver.
1991 Bluebird AARE
1999 Ford Ranger
Andrews,IN

Offline CrabbyMilton

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Re: Gas vs Diesel vs MPG
« Reply #1 on: February 18, 2019, 05:49:56 AM »
Well BLUEBIRD and IC are now offering gasoline engines on their type C models.
The FORD V10 for BLUEBIRD and a PSI V8 for IC.
You have to remember that these newer engines aren't the same types that were the mainstay over 30 years ago. Diesels are still more efficient but not having to deal with DEF and other components may not be worth the higher purchase price unless it's a high mileage bus.
Even though modern diesels are much more cooperative when it comes to starting in very cold weather, gasoline still has the edge there.

Offline buswarrior

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Re: Gas vs Diesel vs MPG
« Reply #2 on: February 18, 2019, 05:51:35 AM »
Cost to purchase and cost to maintain cannot be ignored.

Huge swing back to gas engines in Ambulances, school buses, delivery trucks, rental fleets...

Math showed so much savings in acquisition and care, that the paltry difference in fuel economy never pays them back.

And the gas motor both starts easily in the cold, and makes heat.

I wonder about a day, not far off, where the used RV dealers report they have trouble selling diesel emission equipped rigs....

Priced a DPF replacement recently?

So, higher initial purchase price, and then deeper depreciation, and exposed to emissions maintenance on a used unit?

And deleting the equipment costs money too, and has to be done right.

The marketing manufactured desire for a diesel will slam hard.

Happy coaching!
Buswarrior


 
Frozen North, Greater Toronto Area

Offline chessie4905

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Re: Gas vs Diesel vs MPG
« Reply #3 on: February 18, 2019, 06:05:23 AM »
Anymore, you also need to factor in things def fluid, maintenance on that, a lot more oil in oil changes. Gas engine plugs usually go 100,000 miles now, no def, much less oil in changes, fewer batteries to replace,Easier service on the road, cheaper repairs on engine. UPS used gas engines in their delivery trucks for a long time before using diesels. Just pointing out that there are other costs to consider along with fuel costs. In the 80's, diesel was about 5 to 10 cents a gallon cheaper than gas around here, so I ran diesel cars. My last diesel was a n 03 tdi Jetta. It was reliable,cheap to run, very little in repairs over 225,000 miles I had it. Now that diesel is significantly more expensive, and Jetta diesels aren't reliable like they used to be, I've moved on to gas vehicles, except my 94 6.5 td diesel truck. It'll be my last diesel. New diesel trucks are very expensive to maintain/repair, no matter which brand. And I've mechanic ed on diesels since 1980.
GMC h8h 649#028 (4905)
Pennsylvania-central

Offline DoubleEagle

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Re: Gas vs Diesel vs MPG
« Reply #4 on: February 18, 2019, 11:25:16 AM »
All of this calculating is nice to play with, but it is more relevant with smaller vehicles. In the case of buses, there are a lack of gasoline engines that could power them adequately. In the smaller vehicles, the fuel mileage will still be less for the gasoline engine. The dependability and cost of engines to start and continue to run without major problems during the practical life of the vehicle are what caused many companies to switch. The Ford 6.0 Powerstroke was a good example. I still run a 7.3L IDI, and a first generation 7.3L Turbo Powerstroke without notable problems, despite their age. I do miss the days when diesel was cheaper than gasoline, but I am not making payments on a new $70,000 Diesel Dually, either.  ::)
Walter
Dayton, Ohio
1975 Silvereagle Model 05, 8V71, 4 speed Spicer
1982 Eagle Model 10, 6V92, 5 speed Spicer
1984 Eagle Model 10, 6V92 w/Jacobs, Allison HT740
1994 Eagle Model 15-45, Series 60 w/Jacobs, HT741

Offline chessie4905

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Re: Gas vs Diesel vs MPG
« Reply #5 on: February 18, 2019, 11:31:54 AM »
I had a 1948 ACF Brill IC-41 conversion several years ago. It had a Hall Scott gas 779 cu.in. 6 cylinder. It would run  equal to my Dads 4104. He got 8 to 9 mpg, I got 5 to 6. The Brill looked like the one in the movie Bus Stop, and on models used on the Andy Griffith Show.
GMC h8h 649#028 (4905)
Pennsylvania-central

Offline TomC

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Re: Gas vs Diesel vs MPG
« Reply #6 on: February 18, 2019, 12:54:34 PM »
Now with the advent of direct fuel injection (into the combustion chamber) on gasoline engines, Gasoline engines have come as close to Diesel engines in efficiency than ever. BUT-gasoline will never surpass Diesel in fuel mileage mainly because Diesels have more BTU (heat) per gallon then gasoline (115,000 vs 139,000 [including Diesels more density]). But you also have more smog control maintenance with Diesels, having to add DEF (about 3% of fuel burn).
One main advantage of Diesels now is you'd automatically get an engine that is turbocharged and air to air intercooled. Most gasoline engines are non turbo'd. Turbocharging is an advantage in altitude-most don't derate till 11,000ft. Personally-I'm a Diesel guy. I have a Mercedes 300 Turbodiesel with 542,000 miles on it and yet to overhaul either the engine or transmission. Have a 1985 KW 90" Aerodyne cabover I'm making a motorhome out of with a Caterpillar 3406B mechanical with coolant aftercooler with 1.2 million miles with 2 in frame overhauls. And my bus with Detroit 8V-71 turbocharged with air to air intercooler. My only gasoline car is a 1963 Ford Falcon with 302 and 4spd. Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.

Offline DoubleEagle

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Re: Gas vs Diesel vs MPG
« Reply #7 on: February 18, 2019, 05:28:34 PM »
My only gasoline car is a 1963 Ford Falcon with 302 and 4spd. Good Luck, TomC

I used to cruise in a Falcon Futura Convertible with the 260 V-8, I loved the sound of the engine.  8)
Walter
Dayton, Ohio
1975 Silvereagle Model 05, 8V71, 4 speed Spicer
1982 Eagle Model 10, 6V92, 5 speed Spicer
1984 Eagle Model 10, 6V92 w/Jacobs, Allison HT740
1994 Eagle Model 15-45, Series 60 w/Jacobs, HT741