Math question

[Cardcounter]

With the cost of gas eating away at are profits from going to the casino and playing blackjack what will save you more money?
upgrading your car from 15 mpg to 43 mpg or upgrading your car from 25 mpg to 235 mpg? In the year 2010 vw plans to release a car that gets 235 mpg so it could be a reality sooner than you think!

 

[callipygian]

upgrading your car from 15 mpg to 43 mpg or upgrading your car from 25 mpg to 235 mpg?

It depends on how much the upgrades cost, how much you drive, when you can do the upgrade, and how much gas costs in the future.

The 43 mpg car will use up 15/43 (~35%) of the gas that the 15 mpg car will, and the 235 mpg car will use up 25/235 (~11%) of the gas that the 25 mpg car will. But depending on how many miles you drive, this might not overcome the cost difference between the cars (anticipating that a brand new 235 mpg car is going to be expensive).

If H is the cost of the 43 mpg car (a hybrid), V is the cost of the 235 mpg car (a Volkswagen), M is the miles you drive, and G(n) the cost of gasoline in year n, and the Volkswagen is only available in 2010, then the total cost of the cars are as follows for the next 10 years:

Cost(hybrid) = H + M/43*Sum(G(n) from n = 2008 to 2017)
Cost(Volks) = V + M/25*Sum(G(n) from n = 2008 to 2009) + M/235*Sum(G(n) from n = 2010 to 2017)

Edit: There's a discrepancy between the poll and your post. You ask what will save more gas in the poll, but what will save more money in your post.

 

[SD Padres]

I'm just gonna start walking. We could run a poll on how many calories I would burn.......

 

[Cardcounter]

What saves the most gallons of gas?

My question did not give any specifics on the cost of the cars or anything of that nature I was just asking what will save more gallons of gas?
Regardless of how much the upgrades would cost.

 

[nightspirit]

What is gas costing in the US temporary?

 

[Cardcounter]

You are wrong if you said 25mpg to 235mpg

Instead of thinking in mpg you should think in gallons per mile. If you take 100,000 miles divided by 15 mpg that equals 6,666.66 gallons of gas. If you take 100,000 miles divided 43 mpg that equals 2,325.58 gallons for a difference of 6,666.66-2,325.58=4,341.08 gallons saved for driving 100,000 miles when you upgrade from 15 mpg to 43 mpg. That is the first option.
The second option has
The first miles per gallon are the most important 100,000 divided by 25 mpg which equals 4,000 gallons of gas. Now 100,000 divided by 235 equals 425.53 gallons of gas for a difference of 4,000-425.53=3,574.47 gallons difference.
Option 1 saves 4,341.08 gallons of gas and option 2 saves 3,574.47 gallons of gas! Option 1 saves 766.61 more gallons of gas than option 2 over a 100,000 miles!
My advice would be always upgrade the least fuel efficient car first.
The cost of gas where I live in california is $4.80 a gallon and going up. Two years ago it was only $3.00 a gallon.
The first mpg are extremely important increasing a trucks mpg capacity from 5 mpg to 7 mpg saves 5,714.28 gallons of gas over a 100,000 miles! More than enough to drive a car along side it that gets 18 mpg!

 

[callipygian]

Option 1 saves 4,341.08 gallons of gas and option 2 saves 3,574.47 gallons of gas!

Sure, but your options have nothing to do with the question you asked.

Your example is contrived - you've assumed that both the 15 mpg and 25 mpg car are going to be driven whether they're upgraded or not. This is a highly questionable assumption in that your example purported to be of a single car being driven a certain distance.

In that context, it is unquestionably better to have a 235 mpg car - your savings will be entirely dependent on the mileage of your new vs. old cars.

Now, if, as you've re-framed the question, that the "other" car will be non-idle and driving the exact same mileage while you're driving the fuel-efficient car to Vegas, then you are correct - it is better to upgrade the lower-mileage car first.

However, under the legitimate assumption that driving to the casino will put more miles than daily use, you can look at these figures. Assume that the less driven car is the low mileage car and that it does 5,000 miles per year; the more driven car is the higher mileage car and it does 10,000 miles per year.

Over 10 years,

Option "1":
50,000 miles / 15 mpg = 3333 gallons
100,000 miles / 235 mpg = 425 gallons
Total: 3758 gallons

Option "2":
50,000 miles / 25 mpg = 2000 gallons
100,000 miles / 43 mpg = 2326 gallons
Total: 4326 gallons

It's always better to use the most fuel-efficient car for the longest trips; if you're going to force the miles driven on each car to be equivalent, you should change your OP.