Illusion of MPG

Woah, you mean a car with a higher MPG rating gets uses less gas for every 1000 miles? It's a good thing we got PhDs like this because NOBODY here would have ever figured THAT one out!

 

I've heard this argument many times in the last fey years, that replacing a 10mpg SUV with a 15 MPG SUV saves more gas that replacing a 30 MPG car with a 40 mpg car.

Drive 10000 miles at 10 MPG, it takes 1000 gallons.
Drive 10000 miles at 15 mpg, it tales 666 gallons, saving 333 gallons


Drive 10000 miles at 30 mpg, it tales 333 gallons.
Drive 10000 miles at 45 mpg, it takes 222 gallons, saving 111 gallons, much less than the SUV driver
(excuse my rounding)

OK, if you do the math it's true.
But isn't that what's called a false dichotomy? There is a third option that for many people is a much better option.

Replace the 10 MPG SUV with a 45 MPG Prius.
Then you are saving a whopping 778 gallons in the above example.

Math can be your friend!

 

USED verses SAVED is basically the same as the KM/L verses MPG measure.

One focuses on conservation, the other provides an excuse.

.

 

<Drive 10000 miles at 15 mpg, it tales 666 gallons, saving 333 gallons
.
.
.
Drive 10000 miles at 45 mpg, it takes 222 gallons, saving 111 gallons, much less than the SUV driver>


Here's the correct way to look at these "savings":
666 gallons - 222 gallons = 444 gallons wasted by the SUV driver

It's not how much you save, it's how much you use.

 

Personally, I think a better way is not how many gallons you use in a mile or even 10,000 - it's how many gallons you use in a month. Right now I'm getting 42 MPG (we had a couple of really hot days where I had to drive a lot with the air conditioner blasting full time - normally in the summer it's more), and in the winter I get a lot less. However, since I drive less than 10,000 miles a year, I imagine I use a lot less gas per month than some of you who are getting 60+ MPG.

 

Husband: You spent $1500 at the mall today?!?!?!?!?!

Wife: But I got everything at 25% off! I saved $500!

 

This argument is valid . . sometimes. . .
e.g. Family has 2 cars and can only afford to replace 1 - one is a gas hungry SUV(10-15mpg), one is a normal, relatively economical 4 door sedan(30-35mpg).

In this case, If both cars average the same sort of mileage and they really want to keep an SUV to cart kids, or canoes, or tow caravans or whatever, it works out more economical to get a 5mpg increase on a new SUV, than a 10 mpg on the sedan.

 

I just did the math for myself. I went from a 18mpg V8 truck to a Prius. It is going to save me 356 gallons every 10k miles. Thats like $1500 bucks!

As far as people needing their big SUV. I am buying a beater Bronco tomorrow and its going to stay out on my ranch. No reason people can't pick up a cheap SUV now and park it.

 

it boggles my mind people even still want a vehicle that gets a measily 15 MPG.
astounding. wasteful. stupid.

if you do have one that gets that kind of MPG you better have a darn good reason
for it. Like a construction worker hauling stuff, a snow plow person making good money,
the need to haul 1000lbs of gear, etc...

but alas, that is what? 5% of large vehicle owners in the USA from what I see? Carting
around their lonesome self back and forth from work... sigh

 

Actually, in this case it works out more economical if the family buys a more fuel efficient Mini-Van, I'm thinking a Mazda5.
It aint world's of improvement but it's much better than buying another SUV.
(And you get all the room you need that the SUV doesn't have.)

ZC1

 

I think the argument being made here is that there is diminishing returns on gas savings. Assuming the mileage driven in a year is fixed at say 10000 miles, the gas saving going from a 10 mpg truck to a 20mpg truck is 500 gallons. Where going from a Prius at 50 mpg to a car that gets 10000 mpg (doesn't exist) is only going to save you 199 gallons of gas because the Prius will only burn 200 gallons of gas in that 10000 miles. That is the most you can save by going to a more fuel efficient car.

Diminishing returns is an important concept to understand since your real dollar savings will be huge going from a Large SUV to a Prius. But the saving will not be as much going from a 50 MPG Prius to a 100mpg Prius even though the MPG savings on the later will be greater.

In the same vein your carbon footprint suffers from the same diminishing returns problem. Once you are releasing only 2 carbon molecules per year for everything you do, cutting your carbon emissions in half doesn't really do much.

So to sum up half of nothing is still nothing.

G

 

Or would it be better to replace the 30mpg car with a 50mpg Prius and use the Prius for most of their commuting duties saving the SUV which is worth nothing now as a trade in anyway because of expensive fuel costs for the occasional long journey or on weekends to take the soccer team to the game or trailer towing twice a year.
This is the PC SUV sequestration program.

 

My Prius is on order!. I'm all for green. I have a 2000 Avalon w/107K that gets 19/26 mpg. But I also have an '87 Ford Club Wagon XLT full size van that will be sold when we get the prius. That said, I just get a little tired of the SUV bashing. When the children where young the 8 passenger van was full or nearly full most days between carpooling for work, school, soccer, baseball, etc. or just a family outing, a Prius or even the Avalon just wouldn't have cut it. Also, with today's car seat safety laws, and for the better, I doubt that the Prius would be a car for family of 5 let alone 8. I can't help but feel that many of the SUV bashers aren't big on family relations. Our kids are grown now, married with children. Both have SUV's as one car and a more economical one as a second. We do alot of things together since we are lucky that they live in the area. I suppose we could all take the smaller more economical cars. Or gee, maybe we can all fit the the 8 passenger van or suv. And that also puts less cars on the road. Golly, do you think that might help traffic jam and potentially save fuel. And maybe we have to go in different directions or go at different times and you end up with a single passenger SUV. I admit, there are too many single passenger SUV's on the road. But, that doesn't mean that the driver is necessarily any less green than you are. And you wonder why some people think Prius drivers are snobs. Maybe because of things like SUV bashing and that acting like non-hybred drivers are somehow less, I don't know, thoughtful, intelligent, green.
Sorry if I upset up anyone with my venting. It's just that there's enough finger pointing going around. It's an election year.

 

lol at patsparks, thats wonderful

 

Simply show how much $$$$ need to spend on gas for driving these vehicles, then which dollar amount people would prefer out of pocket?

Current National Avg is $4.067

(Dollar amount was rounded for simplicity)
1000 gallons = $4067
666 gallons = $2709
333 gallons = $1354
222 gallons = $903

 

I'm sorry dear, we just can't afford another child. I only want to spend $903/yr on gas.

or

If we put Johnny up for adoption we, too, could drive a Prius.

or

Gee Honey! If you trade your pick-up in for a Prius and rent a truck @ Home Depot every day for your contrusupplies, you could save $3064/yr on gas.

 

Well put! We went from a van that got 17 (kept it to pull trailer when needed, 150K on it) to one that gets mid 20's depending on the wind due to cubscouts and girlscouts. We also drive a geo (toyota drivetrain-27mpg, again dependant upon weather) for just the family and now a prius!

 

That sounds like experience talking... You have my condolences.

Is that from the official Government Accounting Handbook?

Bob