Sunday, December 02, 2007

Hybrid Gas Comparison (Long)

When I first bought my hybrid—or even ahead of time, when I was just thinking about it—a lot of people told me that they’d heard hybrids don’t actually save that much on gas. That the fuel consumption was pretty much the same as a normal Civic. Well, luckily for me, I was able to look back in my bank account, and see how much money I’d spent on gas with the previous car, for the last 90 days that I had it. And then I tracked how much I spent on gas for the new car, for the first 90 days.

And to all of the naysayers out there, I have only this to say: You were right. I only saved 23%, which is much less than I’d been hoping.

But before I continue, and get to the list of numbers that you’re all dying to see, let me just get this out of the way: I don’t regret buying the new car. In fact, I still love it. It’s a great car to drive, and it does still save me money, even if it’s not as much money as I was hoping. Sure, some of the lustre has come off, since I’m not saving as much as I’d hoped, but still, I love the car.

Now back to the numbers. First off, I guess I should share the money I spent on the two cars. Unfortunately, there is no way to find out how many kilometres I drove for the 90 days in question, in the previous car, so this isn’t really a pure “apples to apples” comparison; it’s just how much money I spent on each car, on gas. That being said, I’m fairly sure the number of kilometres for each car is probably comparable.

CavalierCivic Hybrid
DateGas# DaysDateGas# Days
May 14$53.69 August 12  
May 15  August 13  
May 16  August 14  
May 17  August 15  
May 18  August 16  
May 19  August 17  
May 20  August 18  
May 21  August 19  
May 22  August 20  
May 23$49.479August 21  
May 24  August 22$32.2911
May 25  August 23  
May 26  August 24  
May 27  August 25  
May 28  August 26  
May 29  August 27$29.225
May 30  August 28  
May 31  August 29$28.012
June 1  August 30  
June 2  August 31  
June 3  September 1  
June 4  September 2$35.074
June 5  September 3  
June 6  September 4  
June 7$47.4815September 5  
June 8  September 6  
June 9  September 7  
June 10  September 8  
June 11  September 9  
June 12  September 10  
June 13$50.886September 11  
June 14  September 12$35.7410
June 15  September 13  
June 16  September 14  
June 17  September 15  
June 18  September 16  
June 19  September 17  
June 20  September 18  
June 21  September 19  
June 22  September 20$37.128
June 23  September 21  
June 24  September 22  
June 25$52.0312September 23  
June 26  September 24  
June 27  September 25  
June 28  September 26  
June 29  September 27  
June 30  September 28$34.418
July 1  September 29  
July 2  September 30  
July 3$46.338October 1  
July 4  October 2  
July 5  October 3  
July 6  October 4  
July 7  October 5$33.807
July 8  October 6  
July 9$47.096October 7$33.112
July 10  October 8  
July 11  October 9  
July 12  October 10  
July 13  October 11$30.024
July 14  October 12  
July 15  October 13  
July 16$33.647October 14  
July 17  October 15  
July 18$48.012October 16  
July 19  October 17  
July 20  October 18  
July 21  October 19  
July 22  October 20  
July 23  October 21  
July 24  October 22  
July 25  October 23$34.2712
July 26  October 24  
July 27  October 25  
July 28  October 26  
July 29  October 27  
July 30  October 28  
July 31  October 29  
August 1$49.1814October 30  
August 2  October 31$35.268
August 3  November 1  
August 4  November 2  
August 5  November 3  
August 6  November 4  
August 7  November 5  
August 8  November 6  
August 9$43.218November 7  
August 10  November 8$35.488
August 11$44.232November 9  

The “# Days” columns are how many days it was between fillups.

So how do those compare? Let’s take a look:

Average Fillup:$47.10Average Fillup:$33.37
Average Days Between Fillups:8.09Average Days Between Fillups:6.85

I tried very hard to come up with a good graph, that could compare these numbers. (I know how much my blog readers love graphs.) The best I could come up with was this, where the red line represents gas spent on the Hybrid, and the blue line represents gas spent on the Cavalier:
hybrid comparison line
Or maybe this works better, where again, the red area represents the Hybrid, and the blue area represents the Cavalier:
hybrid comparison area
What you’ll notice, if you look at the numbers, is that I’m filling up the hybrid every 7 or 8 days, on average, except for some occasions where I’m filling up after only 2 or 3. This is because the mileage is much better in the city than on the highway; when I had to take long trips, that involved a lot of highway driving, I didn’t save as much on gas. For example, the weekend that I spent driving back and forth between Toronto, London, and Chatham. On that weekend, I had a fillup after only two days, and then another fillup four days later. (The car has a much smaller gas tank than my old car, which is why I had to fill up so frequently on these trips. I think the mileage would still be comparable to the old car—not less, but comparable.)

Why is the mileage so much better for city driving than highway driving? Well, here are some quick points on how the Honda hybrids work:
  • As opposed to some other hybrids, the gas motor is always on, for the Hondas. (See below for the exception to this rule.) When you accelerate—at any speed, not just at lower speeds—the electric engine kicks in, and helps the car accelerate. This way, the gas motor isn’t working as hard.
  • When the car slows down, it uses kinetic energy to charge the electric motor’s battery. This means that the car never has to be plugged in.
  • When you come to a stop, the gas motor shuts off, so that the car isn’t idling. When you take your foot off the brake, the gas motor comes back on, and by the time you’re ready to push your foot on the gas, the engine is ready to go.
That’s why the hybrid gets so much better mileage in the city than on the highway. With all of the stop and go, including the acceleration, and the fact that the engine can shut off, when you come to a stop, the hybrid technologies shine. When you’re on the highway, and maintaining a relatively stable speed, there isn’t much for the electric motor to do.

So, with this in mind, I decided to play with the numbers in the spreadsheet a bit. What would happen if I had only done city driving, and not taken any trips that involved a lot of highway driving? Then the numbers might have looked a bit more like this:

Civic Hybrid
DateGas# Days
August 12  
August 13  
August 14  
August 15  
August 16  
August 17  
August 18  
August 19  
August 20  
August 21  
August 22$32.2911
August 23  
August 24  
August 25  
August 26  
August 27  
August 28  
August 29$28.017
August 30  
August 31  
September 1  
September 2  
September 3  
September 4  
September 5$35.077
September 6  
September 7  
September 8  
September 9  
September 10  
September 11  
September 12$35.747
September 13  
September 14  
September 15  
September 16  
September 17  
September 18  
September 19  
September 20$37.128
September 21  
September 22  
September 23  
September 24  
September 25  
September 26  
September 27  
September 28$34.418
September 29  
September 30  
October 1  
October 2  
October 3  
October 4  
October 5$33.807
October 6  
October 7  
October 8  
October 9  
October 10  
October 11$30.026
October 12  
October 13  
October 14  
October 15  
October 16  
October 17  
October 18  
October 19  
October 20  
October 21  
October 22  
October 23$34.2712
October 24  
October 25  
October 26  
October 27  
October 28  
October 29  
October 30  
October 31$35.268
November 1  
November 2  
November 3  
November 4  
November 5  
November 6  
November 7  
November 8$35.488
November 9  

(All I did was remove some of the fill ups, that were close to others, and then adjust the number of days accordingly. It’s not by any means scientific, just a “what if” scenario.)

Using these numbers, the comparison works out so that I would have saved about 34% on gas.

Average Fillup:$47.10Average Fillup:$33.77
Average Days Between Fillups:8.09Average Days Between Fillups:8.09

It’s only a coincidence that the average days between fillups ended up exactly 8.09, the same as for the Cavalier.

Still not the 50% that I would have hoped for, but better than I get with a lot of highway driving. If you’d like to see the graphic versions…
hybrid mock comparison line
hybrid mock comparison area
So that’s how the cars compare. 23%. I only saved 23% on gas.

While I’m posting about the Hybrid, I should mention how the cold affects it. A friend of mine was curious, so I’ll satisfy his curiosity. Remember the three points I mentioned about how the hybrid works? Well in the cold…
  • Acceleration is unaffected. As soon as you turn the car on, and start driving, the electric motor kicks in, and starts helping out when you accelerate.
  • When it comes to charging the electric motor’s battery, the car has to warm up a bit, before it will start charging. So when you start the car, in the cold, you’ll just be using up juice from the battery, and not replenishing any, for the first little while. (That being said, for any significant trip, the battery will get back to its fully charged state after a while.)
  • In terms of shutting off the gas engine, when at a complete stop, this doesn’t happen until the car gets fully warmed up. And even then, sometimes you get a “false stop” when the car is almost warmed up; that is, you’ll come to a stop, and you’ll feel the engine shut off for a second, and then it suddenly turns back on. It’s like the engine is saying, “Can I shut off? Yep. No wait! Not yet!”
Just to round off the post, here are some things about this car, that I’m noticing after driving it for a while:
  • The climate control system is great. It has an “auto” feature, where you simply put it to the temperature that you want, and it will take care of deciding when to turn the fan on, and how much, whether the air conditioning should be on or not, whether the air should come out at the windshield, or at your feet, or wherever, etc. It also tries to monitor the humidity in the car, and keep the A/C on when it gets too humid, so that the windows won’t fog up—although I notice that it doesn’t do this quite as well in the winter, so I have to override the “auto” setting and put the air pointing to the windshield, sometimes.
  • I’m absolutely loving the fact that the stereo plays MP3 CDs. That’s a very nice feature. (I’m sure all cars have that, these days.)
  • It took me a while to get used to the digital readout, for the speedometer, rather than the analogue gauge. (I’d still prefer the analogue gauge, I just got used to the digital readout.)
  • I didn’t notice it at first, but the Civic has a lot more room in the back seat than the Cavalier did. This is partly because the Civic doesn’t have the bump on the floor, where the middle passenger would sit. (I’m sure one of my gear-head readers will leave a comment and tell me what that lump is there for, on most cars, but the point is, it’s not there on mine, and my back seat passengers get more leg room because of it.)


David Hunter said...

One other thing I can mention:

The main reason we bought the car was to reduce emissions, not to reduce our spending on gas. They go hand in hand, but it was the emissions we were most interested in. Unfortunately, I have absolutely no way of measuring how much lower the emissions are. I assume they are lower, but haven’t the faintest idea how much lower.

Anonymous said...

That lump is where Jimmy Hoffa is buried. Knowledge is power!