Tracking Gasoline Usage: A Personal Account of Fuel Consumption and Cost

[ThomasT]

In one of their frequent reports about the rising price of gasoline, ABC's "World News Tonight" recently cited a survey claiming that the average American family used $4000 worth of gasoline last year. I'm one of those people who writes down every gasoline purchase in a little notebook, to keep track of gas mileage, so I added up everything for my car (a 12-year old Chevy Prizm, basically a Toyota Corolla in disguise) last year:

9253 miles
252.63 gallons
Total cost $876.47

About a third of that was during a road trip last summer from South Carolina to New England and back. We live within walking distance of where we work, so I seldom drive to work. I do many of my local errands by walking from home or work; occasionally I drive in town (a few miles). About 4-5 times per month, I drive to the next town (about 20 miles round trip) or to the nearest cities (usually 70-100 miles round trip, occasionally as much as 200 miles).

My wife uses her tiny car only for local grocery shopping etc. Whenever we go anywhere together (usually out of town), we use my car. She probably buys gas no more than once every two months, for a total of maybe 60 gallons a year, about $200-$210 last year.

So we spent about $1000 total on gasoline last year. Omitting the New England trip brings it down to about $650.

I used about, oh, maybe $20 worth last month (I'm retired). But I can sympathize with the situations of people who have to spend a lot on gasoline. And, things are, apparently, going to get a lot worse in the coming years.

 

[Ivan Seeking]

... I use a gallon of diesel fuel for every 60 miles, or so...

Hear, Hear!

A few years ago I discovered that the Honda Civic Diesel sold in Europe gets better mileage than the Honda Civic Hybrid [not a plug-in]. Plug-in hybrids may make good sense for local driving, but your any distance, diesel is the way to go. And the efforts to produce carbon-neutral biodiesel from souces like algae and bacteria, look most promising.

There may already be diesel hybrids our there. I know Ford was working on one. When it comes to efficiency, diesel is quite simply superior to internal combustion engines. I know there are variations on the classic ICE that seem to promise higher efficiencies, but diesel is a more-than-proven technology.

 

[cmb]

My regular commute is approx 2 miles urban, 18 miles motorway, 2 more miles urban. I know the route backwards (obviously I know it backwards ... I meant it figuratively!), and I know how to drive it so that the car naturally slows at every point I might get stopped, and brake only a remaining 5mph, maybe, if I do need to stop.

Net result is that a hybrid would serve absolutely zero purpose in this scenario - the extra motor/batteries would just be dead weight. Their only purpose is to regenerate under braking. So by not having a hybrid but driving so you don't need to brake, you'd avoid all that harmful* CO2 that would then float off into the atmosphere in the manufacture of those extra, useless bits.

*(Not my opinion - quoting the EPA's ruling on CO2 emissions.)

I used to have a car with the VAG 1896 diesel engine with variable turbo geometry. VW claimed 43% thermal efficiency from it (and they've made more efficient engines since then!). I used to average 85 mpg on the same route (cold-start to key-off), if I kept my speed under 55mph on the motorway. And this wasn't a teeny car, this was a full 3500lbs mid-sized family car. This makes even a plug in hybrid pointless, from a CO2 emissions standpoint, as it would be more efficient to burn that fossil fuel in the car than in the power station (assuming this sort of efficiency, and non-nuclear/renewable electricity).

 

[xxChrisxx]

I used to have a car with the VAG 1896 diesel engine with variable turbo geometry. VW claimed 43% thermal efficiency from it (and they've made more efficient engines since then!). I used to average 85 mpg on the same route (cold-start to key-off), if I kept my speed under 55mph on the motorway. And this wasn't a teeny car, this was a full 3500lbs mid-sized family car.

Golf Bluemotion?

I don't think my brain to foot neurons would allow me to go so slowly.

 

[Moonbear]

Golf Bluemotion?

I don't think my brain to foot neurons would allow me to go so slowly.

I don't even know who still has 55 mph limits on the highways. Around here, the speed limit is 70 mph, and across the border slows to 65 mph. I only see 55 posted in congested areas where you're more likely to sit in traffic only doing 40 mph anyway, but that's the exception, not the norm.

 

[cmb]

Golf Bluemotion?

I don't think my brain to foot neurons would allow me to go so slowly.

Škoda Octavia. Based on a Golf, with an extended floorpan. The homologated fuel consumption figure for highway was ~70mpg, but it is not difficult to get +20% out of a diesel if you drive like a saint. Patience, dear boy, patience! 55mph or 70mph makes very little difference to the overall time taken, on such a short commute.

In the Škoda range there is now a range of even more economical cars, like Bluemotion but named 'Greenline'. The smaller car in the range, the 2,500lbs Fabia, comes with a homologated highway figure of 95mpg.

 

[jtbell]

I don't even know who still has 55 mph limits on the highways. Around here, the speed limit is 70 mph, and across the border slows to 65 mph. I only see 55 posted in congested areas where you're more likely to sit in traffic only doing 40 mph anyway, but that's the exception, not the norm.

Around here (South Carolina), rural Interstates (motorways) are usually posted for 65 or 70, but most other rural roads are 55. On my local intercity trips, I usually prefer the "other" roads in rural areas because they're less congested. When I approach a city, those roads become more stop-and-go, and I switch to the parallel Interstate, which is now usually 60 or even 55.

 

[xxChrisxx]

Škoda Octavia.

but it is not difficult to get +20% out of a diesel if you drive like a saint. Patience, dear boy, patience!

I drive a MK4 GTI.

Getting tricky to justify at 400miles a week though. I'm looking for a decent diesel, Leon Ecomotive.
Don't think I could give up the power though.

 

[cmb]

Getting tricky to justify at 400miles a week though. I'm looking for a decent diesel, Leon Ecomotive.
Don't think I could give up the power though.

Sounds like you might want a BMW 535d then? Currently delivering 313bhp (0-62mph in 5.5 seconds) with a 53mpg homologated fuel consumption rating.

 

[Jasongreat]

Dont use gasoline, but it costs me about 100- 150$ a week in diesel at a minimum, so atleast 5200- 7700$ a year, but I am sure it is usually over that since I usually average 30,000 miles a year at 20 mpg at @ 4$ a gallon, and most years I am closer to 50,000 miles. Traveling is my entertainment, as well as necessary for most my jobs, a road I have never before been down is one that I just have to travel down and 'short cuts' are my favorite, though I have yet to find a 'short cut' that wasnt longer than the normal route. :)

As a side note, I never pay much attention to fuel prices or my mileage. Imo, it is just the cost neccesary to my way of life, especially living in the west where the next major town is 80 miles away in every direction, and I can spend days in the great basin without seeing a town let alone another person, although a lot of the year 4x4 is neccesary, which also lowers my mpg, but makes traveling far more interesting.

 

[collinsmark]

Since November I've been driving a plug-in hybrid. According to the odometer and lifetime trip meter, so far I've gone 1385 miles (2228 km) on only 0.2 gallons (0.757 liters) of gasoline -- but 0.1 gallons was already on the lifetime trip meter when I bought the car (probably for manufacturer testing), along with just a few miles on the OD.

So at the current rate, I'm getting about 13800 mi/gal (~5870 kilometers per liter).

Of course, that current rate isn't going to last forever. The car automatically goes into gas mode every month or two to keep the hoses clean (which is where the other 0.1 gallons came from), and will eventually go into gas mode when the average age of the gasoline is over a year old. And I haven't gone on any long trips yet either.

Over the long term, I can see myself driving ~5000 miles/yr, and spending $50/yr or less on gas, without much problem.

My electricity bill has gone up roughly $12 dollars per month, depending on the month, so far (I am able to charge up at work occasionally too, if you're curious). So add on another ~$144 for the year, to get my personal transportation energy costs. ~$200/yr total (electric bill + gas) sounds about right.

However, to be fair you would need to look at the increased price paid for the car and then how long it takes to pay down the difference, in fuel savings. I've been shying away from hybrids because it's not clear the pay off is there. As time goes on, I would be interested to hear how this works out in addition to the cost of maintenance; in particular, how long the batteries last and the replacement cost.

Good point. The trouble is finding a good car for comparison. Comparing my car model to a subcompact economy car (as many in the media continue to do) is not a fair comparison. Those cars are either smaller, have far fewer features, or lower build quality. They invariably don't have the punchy acceleration.

I mean sure, a bicycle gets better gas mileage than a Lamborghini Aventador Coupe. But if you had a magic, unlimited energy Lamborghini Aventador Coupe that costs $3000 more (all else being equal as the normal, gas one), you wouldn't compare it to a bicycle. You'd compare it against a normal Lamborghini Aventador Coupe.

The problem is my car doesn't have a gas-only equivalent. The Chevy Cruze is roughly the same size and shape as my car, but much lower torque and a reduced feature set. It's not even in the same leauge (not to mention the Cruze has inexpensive wheels with hubcaps, versus the Volt's 17" alloy rims). That's not a fair comparison. "To be fair," I need to compare it to a car with similar features. So here's what I have.

My car model:

2012 Chevrolet Volt
Width: 70.4 in.
Height: 56.6 in.
Length: 177.1 in.
Front head room: 37.8 in.
Front leg room: 42.1 in.
Front shoulder room: 56.5 in.
Rear head room: 36.0 in.
Rear leg room: 34.1 in.
Rear shoulder room: 53.9 in.
Torque: 273 lb·ft
MSRP from $39,145

Mine's a different color, but you get the idea.

==============================================

The Volt is roughly the same size and interior as this model:

2012 Mercedes-Benz C-Class C250 Sport Sedan (and they both ride smoothly).
Width: 69.7 in.
Height: 56.3 in.
Length: 180.8 in.
Front head room: 37.1 in.
Front leg room: 41.7 in.
Front shoulder room: 54.7 in.
Rear head room: 36.9 in.
Rear leg room: 33.4 in.
Rear shoulder room: 55.0 in.
EPA mileage est. (cty/hwy): 21/31 mpg
MSRP from $34,800

Of course the Volt only seats 4 and the Benz seats 5. But I can't decide whether that's necessarily a negative. The Volt's back seats are like bucket seats which are much more comfortable anyway. Heck, what am I saying; who needs back seats in the first place? What I'm more interested in is torque!

==============================================

The Chevy Volt has the same torque as this model:

2012 Porsche Boxster Convertible
Torque: 273 lb·ft
EPA mileage est. (cty/hwy): 19/26 mpg
MSRP from $65,200

But a car like that can be pretty loud while driving, making it tough to listen to music or have a pleasant conversation. It's often nice to have a quiet ride.

===============================================

The Chevrolet Volt is at least as quiet as this model:

2011 Rolls-Royce Ghost Sedan
EPA mileage est. (cty/hwy): 13/20 mpg
MSRP from $246,500

===============================================

Notice I didn't mention horsepower. My Volt's maximum speed is 100 mph as it is, and I have no desire to go that that fast or faster (I live in a modestly congested city -- there's always traffic. The only cars moving 100+ mph are the ones falling off an overpass). Horsepower has more to do with max speed than acceleration. What I'm interested in is instant, quick acceleration at surface street speeds; and that is where torque dominates.

So what do you think: When calculating my car's "increased price paid," should I perform a simple average on the MSRPs and EPA mileages of these other models, or should I do a weighted average based on my personal feature preferences?

[Edit: sources for all specifications above are from edmunds.com]

 

[cmb]

About the same size as the 83mpg Golf 105bhp 1.6 diesel Bluemotion. The torque is a bit meaningless as it all depends on the gearing as to what torque you actually see at the wheel.

So the question now, then, is if the Golf emits less than 99g of CO2 per km travelled, then if you use the national average mix of electricity then how much CO2 is emitted in generating that much electricity to make the Volta go a kilometer?

 

[cmb]

Just checking the prices of the Golf versus Volt.

In UK you can get the Golf for £17,517
In 2012, you'll be able to get the Ampera for £38.995

So that's a £21,478 difference.

The best interest on your money at the moment here is ~4% (Halifax), so you'd get £860 pa just on the interest of the price difference, which, even at UK's exorbitant diesel price of £6.40 per gallon, will provide you with 134 gallons of diesel a year, just funded on the interest alone of the difference, which'd be fuel enough for the Bluemotion Golf of around 10,000 miles.

I think the Volt/Ampera is great, but at the moment I'd buy the Golf and pocket the purchase difference.EDIT: Just done the following table comparing it with the Golf's sister, the Skoda Octavia (which is slightly bigger and matches the Volt better). I also picked the vRS model to give you better performance than the Volt. I used your data, and added a few extra lines:

 

[QuarkCharmer]

Last year I put 4800 mi on my newer honda at 30mpg or so, and 500 mi on an older car that gets around 20mpg. That's about 185 gallons used, at an average of around $4 per gallon here, so that's around 740 dollars annually for me, a single individual. Granted, I travel every day to class by bike. I started that about mid last year, so really for me alone I should be close to a grand a year if I drove everywhere.

So far this year I have only put 700 miles on the honda at 30mpg (which is now sold), and about 400 on the older car at 20mpg, so that's about 173 dollars since Jan 1. I have really upped the distance that I bike though. If I need to go anywhere and it doesn't matter if I smell nice or not, and I think I can make it, I will bike. I went from doing 5-8 miles each outing for exercise 6 months ago to around 20-30 miles twice a week, not counting my short 1-2 mile trip to the campus 5 days a week.

In 2009 I had a little sports car that did no better than 13 mpg, and around 11 on avg. I put 7000 miles on that car that year due to frequent trips upstate. That cost me around 2500 bucks if gas was 4/gal then, but that was also during the great gas-price-panic summer when prices hit 5.50 here. Shocking really.

Here's a thread from last year where I contemplated purchasing a road bike for campus-travel. https://www.physicsforums.com/showthread.php?t=529533
Bike has already paid for itself 5 times over. Best purchase I have made in the past 5 years for sure.

 

[jtbell]

I went from doing 5-8 miles each outing for exercise 6 months ago to around 20-30 miles twice a week, not counting my short 1-2 mile trip to the campus 5 days a week.

That's pretty much what happened to me in grad school. I joined the local bicycle-touring club and ended going out with them usually twice a week, once for 20-30 miles, and once for 50-60 miles, over and above using my bike for most of my basic transportation in town.