10mpg truck vs 25mpg car: economics help
 

Greetings all.

I am currently doing some serious math comparing my dads truck, which gets 10mpg on a 22 gallon tank (I know, I know. Terrible. Even HE knows it's terrible) with a 12 gallon tank hypothetical car which gets 25mpg (trying to keep it reasonable for him. 25mpg is realistic for any car) to try and scare him into getting a better car. So at $4/$5 per gallon, and if the hypothetical car costs $3000, how long will it take to pay itself off. I would try and do all the math right now, but my mind is foggy, and I know if I don't ask now, I will forget and procrastinate. So far, I have figured out that at $5/gal my dads truck will go 2 miles/dollar, and the car will go 12 miles/dollar, and, going further, the car will cost 2.5 times less than the truck to fill up.

Correct me if I am wrong please, and give me a hand too. We are trying to save money to help pay off our house for our inevitable move to California within a few years. If you can help put it into an economic context to help him understand how much money he'll save long and short term if he buys a $3000 economy car. I understand insurance will be a factor, but I will try to factor that in myself.

BTW he used to drive more highway miles than anything, but since he started working from home he rarely drives on the highway, so the current numbers are probably significantly lower.

Thank you all! Happy hypermiling!

How many miles does he drive a month?

Honestly, I have no idea. I would assume 500 miles, since he fills it up almost once a week, but he also takes my step-mom and drives her Corolla while on short errands. The real highway miles now are actually when he drives to-from the airport.

When I like to make fun of guzzler drivers (almost always!) I like to say that for the same money, for every 100 miles they go, I go 900 miles (or whatever the numbers say)... and are you really enjoying each mile 9x more than I am?

Man, you guys had better be saving your money- Cali is EXPENSIVE!!! :eek:

Assuming dad puts 20 gallons into his 22 gallon tank every week, he drives 800 miles/month, about 10,000 miles/year. He'll buy 1000 gallons at a cost of $4000-$5000.

A 25 mpg car will consume only 400 gallons to go 10,000 miles, at a cost of $1600-$2000. Add the $3000 cost of the car, and it pays for itself the first year. If dad drives more, or the car gets better mpg, the higher mileage car pays for itself even sooner.

The truck uses 0.1G/mile and the car 0.04G/mile, the difference is 0.06G/mile.

At $5/G you are saving $0.3/mile.

You'll get you money back after 3000/0.3 = 10000 miles.

At $4/G it'll take 12500 miles.

Making cost calculations difficult is the main drawback of using MPG instead of GPM.

If this is for economics you have to consider a few things:

- if the truck is reliable. Any $3k car may need some expensive work done to it.

- 25 mpg for a car? Maybe for a really small one but certainly not for every car. Around town I think my V6 Fusion is closer to 20 mpg. My ScanGauge just arrived yesterday and I haven't hooked it up yet.

- If you are going to also keep the truck then you also have an additional vehicle to insure.

- Are there ways for your dad and step-mom to simply swap vehicles making the total cost less for the family.

Divide the cost of fuel by the MPG.

My Altima say 33 MPG. Gas at $4.00 per gallon.

400/33 is the cost per mile in fuel.

12.12 cents a mile. $1,212 per 10,000 miles

My bike at 80 MPG.

400/80 is the cost per mile in fuel.

5 cents a mile. $500 per 10,000 miles

Your truck at 10 MPG.

400/10 is the cost per mile

40 cents per mile or $4000 per 10,000 miles.

regards
Mech

25MPG is easily achievable in a 4 cyl midsize car with a manual transmission, an auto would make it harder (especially for an older car) but still very much doable. Unless towing, a V6 in a midsize car is overkill.

I imagine that KITT222 is probably looking at something smaller like a civic, so 30MPG wouldn't be unreasonable to expect.

my girlfriends focus gets around 27-28 MPG with her driving around town, and will likely get 33-35 MPG on the highway with me driving (we'll find out during this weekends roadtrip). it has enough room for both of our duffel bags of stuff, our dog (with crate food, toys, etc) and plenty of room for us (comfort wise), it's a little difficult for me to get in (since i'm 6'4") but once i'm in, i'm good to go.