Recommendations on a new green car purchase?
June 26, 2012 12:03 PM   Subscribe

thinking of buying a new car. Priorities are : 1) green (fuel efficient) 2) safe 3) can seat 4-5 4) ideally will hold an 8-9 foot surfboard inside (not essential) 5) I drive about 30 miles a day Amongst other options in looking at the new prius plug-in, how does one really calculate per mile costs? My concern is that in Hawaii, where electricity costs are through the roof, the savings accrued through plug in option are minimal and the costs not minor. What other vehicles would one look into? I have the Hyundai Elantra, Fit, regular prius
posted by dougiedd to Shopping (26 answers total)
Since the overwhelming majority of electricity on Hawaii is produced by burning oil, it is not green at all to use electricity to power a car there (unless you have a renewable source of electricity). It is better to burn that oil directly in a car engine.
posted by ssg at 12:10 PM on June 26, 2012

We bought the 2011 Prius (one of the lower-end models) and are very happy with it. Drive about 40-50 miles/day, getting 50 mpg in mixture of city and highway driving.
posted by lukemeister at 12:11 PM on June 26, 2012

The Fit, um, fits all five criteria. It's pretty fuel-efficient -- I drive about 45 miles a day, and I routinely get about 38 miles to the gallon. It's about as safe as a small car is going to get, will seat 4 with comfort, and will seat 5 fine as long as someone's skinny enough for the middle seat in the back. I've also gotten 8-foot boards in with a few inches to spare, though you will have to lay the front passenger seat down to do so (you definitely couldn't bring 4-5 people and the surfboard.)
posted by vorfeed at 12:15 PM on June 26, 2012 [1 favorite]

OK, the Prius Plug-in Hybrid has an expected total range of 540 miles. So every 540 miles, you need to both fill the tank and charge the battery, right? According to the wikipedia page, "the battery requires approximately 3.4 kWh for a full charge." According to other sources the tank size is 10.6 gallons.

So the cost per mile of driving a Prius plug-in would roughly be:

(3.4 kWh * Price of electricity per kWH + 10.6 gallons * Price of gas per gallon)/(540 miles)

If Hawaii's main source of electricity is gasoline, I would be surprised if this ended up cheaper than a straight hybrid, even though the range is longer.
posted by muddgirl at 12:20 PM on June 26, 2012

The Honda Insight is essentially the Fit hybrid. I adore my Insight, and generally get 45+ mpg.
posted by hydropsyche at 12:30 PM on June 26, 2012

Burning oil for electricity may be a factor in considering electric/hybrid cars in HI seeing as 90% of electrical production comes from burning oil. But, it is worth researching which has greater efficiency the electrical plant or automobile. I would challenge ssg to provide a cite for his/her assertion. They may well be correct, but it doesn't look like it is slam dunk obvious.
posted by edgeways at 12:32 PM on June 26, 2012 [3 favorites]

My boyfriend recently bought a Prius Hybrid - the Prius V (not a plug-in) after considering the cost of fuel compared to a regular car. Plus he has the same needs as you, though he carries his surfboards on a roof rack, not inside since I think he rides mostly longboards.
posted by marylynn at 12:38 PM on June 26, 2012

My mom, literally yesterday, bought a 2011 Mini Cooper S with whatever the extended back end is called (like 6 more inches in the trunk end, not the one that's overall bigger). It's supposed to get 39 MPG but isn't a hybrid or diesel, has a five star crash rating (not to mention that it's basically impossible to roll and has ceiling airbags, which I've never even heard of), and it's super fun to drive (sport mode paddle shifters! Hawaiian coastal roads!). I drive a 2005 Prius myself, and it's basically the same car, but somewhat safer and far more fun.
posted by cmoj at 12:55 PM on June 26, 2012

Since the overwhelming majority of electricity on Hawaii is produced by burning oil, it is not green at all to use electricity to power a car there (unless you have a renewable source of electricity). It is better to burn that oil directly in a car engine.
I don't immediately have numbers handy, but I'd be very surprised if the thermal efficiency of a car engine was not quite significantly lower than that of a oil-burning power plant, for a number of reasons. There are, of course, some additional efficiency losses from actually generating and transmitting the electricity, but they should be pretty small and I would still bet you end up at least slightly ahead (before accounting for the additional financial and environmental costs of the car batteries &etc). That being said, it is true that the dirtier or more expensive Hawaii's electricity is, the more that will reduce or eliminate the benefits of having a plug-in hybrid.

muddgirl's equation is only correct in the case that you charge the battery & fill the tank, and then drive until both are completely depleted before refilling either. This is a very unlikely use scenario - you need to consider how often realistically how often you'll be able to benefit from the EV mode mode and to charge the car afterwards.
posted by kickingtheground at 1:00 PM on June 26, 2012 [1 favorite]

My equation wasn't meant to calculate actual costs based on usage, but to be used to compare potential cars across the board - it might be a lower bound. To calculate the upper bound, the average commute is about 30 miles and the range of the battery-only is 11 miles, so we could also assume that he's doing one full charge per day, plus another 20 miles of hybrid driving, but that starts to get in to teasing out equivalent mpgs.
posted by muddgirl at 1:08 PM on June 26, 2012

There's always the Chevy Volt, which theoretically should get you there and back again on just battery.
posted by Atreides at 1:26 PM on June 26, 2012

Buying a new car of any kind is far less green than buying a used car that's fuel-efficient.
posted by kcm at 1:30 PM on June 26, 2012 [4 favorites]

VW Jetta diesel wagon -- 30/42 mpg.
posted by wutangclan at 1:35 PM on June 26, 2012 [4 favorites]

I came in here to make the VW TDI diesel wagon recommendation, we've got one and love it, but though I can get 42MPG highway on long trips (my wife gets closer to 38 in her commute with stop-and-go traffic), thats diesel gallons. EPA says 8.81kg of CO2 emitted per gallon of gasoline, 10.15 kg of CO2 per gallon of diesel, so that says that the effective MPG in gasoline gallons in the context of carbon load is closer to 33-36.5MPG.
posted by straw at 1:55 PM on June 26, 2012

The Honda Insight gets overlooked as a great alternative to the Prius. It has been one of the best rated cars on owner satisfaction (well, 2nd, after the Mini) on a few lists I've seen. The Fit is also a great option.

I would suggest diesel too, but I don't know the price of diesel in Hawaii, if that makes it too expensive. I think they are bringing the VW Polo to the US soon, and that can easily get 60-70mpg.
posted by neveroddoreven at 2:52 PM on June 26, 2012

My experience is that the Insight is slightly smaller than the Prius - not as much head room especially (important for fitting big stuff). It is slightly less comfortable to seat 5 than the standard Prius, and it's city MPG is not as good (my husband drives about 50 miles a day of city driving and he easily gets 48-50 mpg). But price has to be factored in.

I would, with a straight face, recommend taking your board on test drives if storage space is even moderately important.
posted by muddgirl at 3:01 PM on June 26, 2012

I just got a Mazda 3 hatchback with the skyactiv engine. It has a good amount of storage space, but I'm not sure if it'll fit a surfboard. Otherwise I think it meets your criteria plus it's fun to drive.
posted by mullacc at 3:11 PM on June 26, 2012

It seems quite obvious to me that the Prius will be more efficient by itself than with electricity generated by burning oil, but since no one else wants to look at the numbers: the plug in Prius gets 4.7L/100km in hybrid mode, 2.5L equivalent per 100km in electric mode. So in order for the fuel oil -> powerplant -> electricity route to be more efficient, the plant would need to be operating at more than 53% efficiency, which obviously no fuel oil thermal plant is even close to, let alone once you account for transmission losses, not to mention all the secondary energy costs related to building and running a power plant, etc.
posted by ssg at 3:35 PM on June 26, 2012

straw, that is a good point. Burning diesel puts out more CO2 as well as energy, compared to gasoline. However, auto-grade gasoline requires intensive, multi-stage refining, whereas diesel is mostly a straight distillate of crude. End-to-end, diesel is still significantly better...ignoring the slightly inconvenient issues of particulates, carcinogens, etc :-)
posted by wutangclan at 4:09 PM on June 26, 2012

It is not that people don't want to look at the numbers, but that the numbers are not readily apparent. I'm not even saying your are wrong on your basic assertions, but that just making blanket assertions is not the same as showing why your assertions are correct.

So... the plug in Prius holds a charge of 4.4 KWH. On which it can travel ~11 miles.
1 Barrel of Fuel oil produces 610 KWH, or 14.5 KWH per gallon.
4.4/14.5 = .3
To charge the Prius it takes .3 of a gallon of fuel oil. Or say 33 miles traveled on 1 gallon of oil.

Being generous 1 barrel of medium to good quality crude oil (42 gallons) equals about 12 gallons of gasoline (28.5%).

Setting aside that fuel oil cannot produce gasoline in even remotely the same %, lets just pretend they are burning mid grade crude oil to make electricity...

1 gallon of oil (33 electric Prius miles) converted into gasoline = just over a 1/4 gallon of gas. So we're talking about 132 miles per gallon equivalency. And this is allowing ALL kinds of slop for transmission loss, and isn't taking into account the oil used for power power production is not the same as oil for gas production.
posted by edgeways at 7:29 PM on June 26, 2012

This is getting to be a bit of a digression, but the number you are looking for is the miles per gallon equivalent, which is 95 Mpge or 2.5l/100km for the plug in Prius, according to the EPA. That is just the energy equivalent, not accounting for the (very large) losses burning oil to make electricity. I'm not sure what you are trying to calculate exactly, but it obviously disagrees with the EPA's number.
posted by ssg at 8:48 PM on June 26, 2012

Best answer: I started writing a long math filled post and gave up. Basically...

Based on napkin math on battery electric vehicles, it seems the "break-even" point is using heavy oil for electricity production. Basically, if your country uses less polluting power than oil, it might be worth it to use electric vehicles to reduce CO2 emissions. If you use more polluting power sources (basically coal) then electric vehicles actually cause more CO2 emissions than gasoline. If oil - like Hawaii - it's about equal. (napkin math based on 15kwh per 100km of the Nissan leaf, co2 per kwh generated based on wikipedia estimated). So on this point I'm sorta in agreement with SSG.

The Prius isn't a BEV, it's a HEV (hybrid) and the point of hybrids is to recapture kinetic energy, they're not particularly efficient at running on pure electric mode. Also, be aware that while the batteries are rated at say 4.4kwh, virtually all batteries cap out at 25% capacity so the Prius only uses 3.3kwh to get its stated maximum range and hence only needs 3.3kwh to recharge.

That derail being over with...

There's been a big convergence in vehicle quality and capability in the last 5 years. It's become increasingly difficult to buy a current model "crap" car from the biggest players - I can't think of any current model c-segment cars from GM, Toyota, Ford, Honda, Mazda, Volkswagen, Hyundai, that are so bad I would go out of my way to warn you away from, or so good that it's a no brainer for everyone to buy. It's become commodified in a way, a bit like watches and t-shirts, no one really buys them for their engineering, people buy them because the design is in harmony with their personal ideals of aesthetics. Sure, enthusiasts will "swear" by the merits of their chosen brand - Focus for its handling, Toyota for reliability, etc, but my feeling is the average user will be best served by buying the one that looks most beautiful in their eyes and that meets their minimum requirements - they're all going to get 4-5 stars in NCAP, all going to have pretty good fuel efficiency.
posted by xdvesper at 9:13 PM on June 26, 2012

I love my Toyota Yaris. It's the hatchback version and is strictly a commuter car. The hatchback version looks the best in my opinion.

It's cheap, too.
posted by shew at 9:24 PM on June 26, 2012

A couple of the newer crossovers have pretty reasonable mileage- you may want to check out the Honda CRV and the Mazda CX-5. Both of these achieve 30mpg+ on the highway, have comfortable seating for 4-5, and have plenty of room for extra stuff compared to an Insight/Prius.
posted by gatsby died at 6:51 AM on June 27, 2012

We loved my wife's Honda Fit, could get anything in it and it did great mileage, not to mention very safe (she got rear ended in it and walked out without even a sore neck).
posted by arcticseal at 8:00 AM on June 27, 2012

just got a honda CR-V a week ago today after going out with the intentions of getting a fit. Its bigger, it sits more people, it has more gets less gas mileage. Highway is great but your not really flying around at 65 all day long in Hawaii anyways...So streets are the suck on the low end 20MPG to about 24 tops on streets.
posted by couchdive at 4:42 PM on June 27, 2012

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