Not all hybrids are born equal!

[Brian]

The fuel consumption of hybrid cars are often just as bad, or even worse, than many conventional cars. The following is a list of hybrids and their approximate 33/33/33 highway/rural/city aggregate consumption (derived from a number of sources) in litres/100 km : EPA air pollution score (based on emissions quality, not on volume)

Toyota Prius 5.4 : 8
Honda Civic Hybrid 5.6 : 9

Nissan Altima Hybrid 7.1 : NA
Toyota Camry Hybrid 7.1 : 8
Ford Escape Hybrid FWD 8.1 : 8
Ford Escape Hybrid 4WD 8.9 : 8
Mercury Mariner 4WD 8.9 : 8
Honda Accord Hybrid 8.9 : 9 (discontinued)
Saturn Aura Hybrid 8.9 : NA

Lexus RX 400h 2WD/4WD 9.2 : 8
Toyota Highlander Hybrid 2WD/4WD 9.3 : 8
Saturn Vue Hybrid 9.4 : 6
Lexus GS 450h 10.5 : 8

Chevrolet Silverado Classic 15 Hybrid 2WD 14.2 : 3
GMC Sierra Classic 15 Hybrid 2WD 14.2 : 3
Chevrolet Silverado Classic 15 Hybrid 4WD 15.0 : 3
GMC Sierra Classic 15 Hybrid 4WD 15.0 : 3


As expected, the Prius and Civic are way ahead and the big pick-ups are worst, from the point of view of consumption, each in a class of their own. I wonder why the two Honda's in the list are less polluting than all the Toyotas and Lexus + a few others and why the pick-ups are very much worse, according to the US EPA?

The colour coding is arbitrarily chosen by me: green = <6 l/100 km, blue = <9 l/100 km, black = <11 l/100 km and red = >14 l/100 km (none fitted in orange <14 l/100 km).

[Darin]

Although I'm disappointed by the efficiency of small car offerings these days, I will say that having a Luxury hybrid SUV instead of the usual in areas with dense traffic will save as much gas as a small hybrid car uses every year. Not to say that using something the size of a small house to transport a single person with minimal cargo is a good idea, just that hybridization across the board tends to be good in terms of minimizing the hit from heavy traffic wrt fuel consumption and emissions.

[Brian]

Darin

The hybrid SUVs are conscience-appeasers designed for the feel-good market, while still keeping up with the Jones's. They still consume twice the fuel than a real economy vehicle.

The ones that really get me are the four pick-up trucks marked in red above. They are no more true hybrids than a Ford Model T. They are exactly the same, including the engine and drive train, as their non-hybrid counterparts except they have a starter motor/generator and a 48 V battery. They have no electric motor in any form of drive train. The regenerative braking charges the battery. The engine stops when the vehicle is stopped and starts as soon as you lift your muddy hoof off the brake pedal, using the special high-power starter motor. In other words, if you are driving under conditions when you never stop (highway or normal rural roads), the fuel consumption is exactly the same as the ordinary versions. In urban stop-start traffic, you will get a marginally better consumption. Calling these vehicles 'hybrids' is a scam; I guess they are designed to appease redneck pick-up drivers who probably don't really know the difference.

[Darin]

While a Hybrid SUV (the hybrid pickups are pretty lame) getting ~25mpg does consume twice as much fuel as a Prius getting ~50mpg, they're both fairly inefficient compared to the 3L Lupo, or the supposed 1L Lupo. The point being that any improvement is better than a kick in the head. That being said, just about everything I see I tend to  classify as greenwashed, including compact hybrid cars, since they're still being used 90+% of the time to transport a single individual with minimal cargo. Hell, we've been dancing around 50mpg ever since the early 80s, with any and all advances going towards larger vehicles with more power/features, not a good idea imo, and to a much lesser extent lower emissions, which is a great idea imo. A hybrid SUV is to a Hybrid compact as a Hybrid compact is to a wacky economy car some guy threw together as a wacky economy car some guy threw together is to the VW 1L prototype.

[Brian]

I'm certainly not into wacky cars. Much of what the guy in your link has done would be illegal in Europe, where cars are officially homologated and modifs approved. For example, he has changed his hub caps and air flow generally. To get this approved, you would have to prove that brake and engine ventilation was not affected and he would certainly never be allowed to run on narrower tyres. Coasting with the engine disengaged is also an offence.

Of course, people can get extraordinary figures. You quote the Prius. But some people are getting extraordinary figures with that, as well:
mpg (US)    Current mi    Starting mi    Tanks
99.0               5,560         1,462          3
76.5               6,075             0            11
71.8               12,158            0           18
Link

And you can hardly compare the Lupo 1 l/100 km, which is a concept vapourware car, with a Prius, which is a real car, capable of transporting 4 persons with baggage and a dog a longer distance in relative comfort and safety.

With all due respect, I feel this discussion should be about off-the-shelf 100% fuel-driven cars that anyone can buy and use without modification.

[Darin]

I know a couple (krousdb and diamonlarry) of the Prius drivers you linked coast with the engine disengaged, and most likely all of them do, since it's the only way I've heard of to optimize BSFC over a relatively low range of speeds in the Prius. Cars came from the factory with freewheeling transmissions, so coasting with the engine disengaged may be illegal over the pond just like it's illegal here, but it's as illegal as jay-walking when I cross the street to get my mail. In terms of body modifications, what you're referring to sounds pretty draconian. Over here the driver can screw with anything except for the emissions system according to federal law, and states dictate what can fly in terms of modifications to the body. However, most things are allowed provided law enforcement can still identify the car and nothing poses a danger to the driver or others.

The 1L Lupo is scheduled to come out in 2010, and the prototype performed as expected, so I don't see how it's vaporware. It may not make it to production, but it was certainly built and tested. In terms of production cars the 3L Lupo is capable of ~100mpg@55mph, something that just about any hybrid less the Insight is hard pressed to achieve. What's the difference between this car/the Insight and current hybrid compacts? It's not as fast, not as comfortable, doesn't have all the bells and whistles, etc... It's closer to the economy cars of the past than any current offerings. My point is that just because something is better than something else doesn't mean it's very green, Carbon wise, even compared to current market offerings. I would say, for the vast majority of drivers, having a two passenger kei car ala the 1L prototype for most use with an older four door for group trips would save far more fuel than going from a compact that gets ~30mpg to a hybrid compact that gets ~40mpg.

P.S. Don't make start ranting about the loon on an electric bicycle powered by a solar panel.

[Brian]

I could not possibly afford the road tax and insurance on a small super-economy car AND a family car. I MUST compromise with a single car for purely economic reasons, so I have to choose one which will do everything that I need it to do, or as near as I can get. Hence I traded in the Honda CR-V, which was near-ideal, bought new in 1998, against a Civic Hybrid, which was slightly less ideal (mainly dog space), with about half the emissions. Both 5 seats, same size (except for height), the SUV was lighter, believe it or not!

[Brian]

I know a couple (krousdb and diamonlarry) of the Prius drivers you linked coast with the engine disengaged, and most likely all of them do, since it's the only way I've heard of to optimize BSFC over a relatively low range of speeds in the Prius.

I can't answer for a Prius as I've only test driven one. With a HCH, the only thing you're likely to do by putting it in neutral is to increase your consumption! It is designed to coast fairly freely, with the engine turning with all valves open and all juice off. Obviously, you have the ordinary rolling and air resistance plus a small amount of essential battery charging. On level road with a good surface, I guestimate that it would take between 300 m and 400 m, starting at 80 km/h, to actually come to a stop, during which time the battery would be topped up 10%.Even with a slight down gradient, one can maintain speed or even accelerate. This is disconcerting at first, when used to a conventional car with engine braking, but one quickly learns to take advantage of it, e.g., when approaching traffic lights. Of course, as soon as you touch the loud pedal, the engine resumes normal functioning.

What would happen if you went into N? You might gain a few metres, but your battery would still charge, because the engine would be idling and thus consuming fuel. You therefore are swapping kinetic energy for chemical energy needlessly and your consumption would probably rise!

Driving in N is, of course, forbidden. I remember the Rover 60 c. 1950 actually had a freewheel on the drive for a few years. Drivers were recommended not to use it for driving in hilly terrain, as the brakes would be prone to fading.

Edit: My memory is bad. The Rover 60 was 1948-49 and the freewheel was there, but inherited from earlier models.

[Darin]

I dunno about whether or not P'ing and G'ing would help out w/ fuel consumption for a HCH since it already has a CVT, which is nice because load can be optimized most of the time, but at the same time a bit of a disadvantage since it's probably lossy compared to other direct drive transmissions. It seems that there could be an advantage with different driving styles, but who knows? I do know that for any vehicle, it will only help provided the engine and/or drivetrain are relatively inefficient at some load. Above certain loads, there's no point. That being said, the Prius is essentially a single speed from the engine's POV, and provided the speed is low enough, if the driver can accelerate up to some speed using only engine power, then let up on the pedal and have the car coastback down to a lower speed, or kill the engine manually and have the car coast back down to whatever speed, w/o getting the inefficiencies of the NiMH pack involved, efficiency can jump significantly compared to driving normally at the same average speed.

The pulse and glide technique seeks to minimize the amount of time that the engine runs, and minimizes power flowing to and from the battery. The pulse refers to deadband acceleration (no flow to or from the battery) up to 40 mph. Next comes the glide (engine is stopped, no flow at all) where the speed slowly decreases to 33 mph. The cycle continues until a stop is required. At such time the brakes are applied and some regenerative braking helps to maintain the battery level. Brakes are also applied if a downhill stretch causes the speed to exceed 40 mph.

[Darin]

I could not possibly afford the road tax and insurance on a small super-economy car AND a family car. I MUST compromise with a single car for purely economic reasons, so I have to choose one which will do everything that I need it to do, or as near as I can get. Hence I traded in the Honda CR-V, which was near-ideal, bought new in 1998, against a Civic Hybrid, which was slightly less ideal (mainly dog space), with about half the emissions. Both 5 seats, same size (except for height), the SUV was lighter, believe it or not!

While this may be the case in some places, it can work in others. The states alone account for a fifth of all the autos on the road, and most people here can afford to have multiple cars. Depending on location, it may or may not be viable, But... Where it is viable it would undoubtedly reduce traffic congestion, pollution, and fuel consumption if implemented properly.