The Curious Lack of Ultra-Efficient Hybrid Vehicles

	Written by Luke Leighton 			
	Nov 02, 2011 at 10:50 AM
	Originally published on

With Electric vehicles receiving a lot of attention, it is very strange to look at the available commercial offerings and find that there are a few that can do over 80mpg (such as the infamous GM EV1), and very few that do the equivalent of 140mpg (Renault's Twizy and the Aixam MEGA). In fact, there is only one vehicle in the world with a Combined Urban Cycle of over 300mpg: the Volkswagen XL1. However although VW's XL1 is a proven concept, it has yet to be put into mass-production.

Even those vehicles which have really good fuel economy (or equivalent), such as the Renault Twizy, are limited in some way: the Twizy is pure electric (limited range), and the Aixam Mega has no gearbox (limited speed) as well as being pure electric (again, limited range). On top of this, there's a hidden skeleton in the E.V. closet: the environmental impact of the batteries. Pure Electric Vehicles typically need to have anything up to 40% of their weight as batteries, just to be able to move the vehicle, and its batteries: the passengers are added almost as an afterthought. Those batteries have Rare Earth Metals (Lithium) or Heavy Metals (Nickel). Lithium is poisonous, caustic, not to mention costly, and spontaneously catches fire if given access to both water and oxygen.  Nickel is at least stable, but that stability comes at a price of being incredibly poisonous and, like all Heavy Metals, is almost impossible to clean out of the environment. Lead is not much better. In other words, even if you wanted to buy a truly environmentally-friendly affordable ultra-efficient Hybrid Vehicle today, you simply can't.

Every single Hybrid or pure Electric Vehicle actually in production today is either affordable but not environmentally-friendly, or is subsidised, or is affordable but has limited range or limited top speed, and absolutely none of them have a "Combined Urban" or even a top best-case fuel economy figure remotely approaching 200mpg. The Toyota Prius, the Nissan Leaf, the Chevrolet Volt: these vehicles have near-identical technical characteristics. Similar weight and similar losses to drag resistance mean that the fuel economy is stuck around what would normally be considered to be exceptional: 70 to 80mpg.  These vehicles have had significant development put into them, to get to where they are, and they're mentioned solely to illustrate that their fuel consumption is almost four times worse than the state-of-the-art VW XL1. At least, however, they're production cars.

The question is why, especially after several decades of Research and Development into Electric Vehicles: surely, a vehicle should be on the roads by now that is green, affordable, has long range and great fuel economy.

Is it even possible to have Ultra-Efficient vehicles?

This question is critical.  Is it technically possible, using known, proven and crucially low-cost mass produced components to create affordable, desirable, safe and also Ultra-Efficient Long-Range Hybrid vehicles?

The key issue in answering such a question is that because such a vehicle doesn’t exist, a definitive answer simply isn't available, but here are some tantalising answers which almost come close, helping to show that it might actually be possible:

●        Volkswagen’s XL1 Concept car almost answers the question just on its own, except that it has ultra-light-weight Magnesium Alloy wheels which have yet to be put into mass-production, and its bodywork is still Carbon Fibre.  It also only seats 2 people.

●        Aixam's MEGA and Renault's new Twizy show that it's possible to get high fuel economy figures and also be affordable, by significantly reducing weight.

●        The MEGA weighs 600kg, is restricted to 4kW (and 40mph), but seats 4 people and has a fuel economy equivalent to 165mpg.

●        VW's XL1, the GM EV1 and the Honda Insight all show that production cars can now be designed with good aerodynamics.

●        Aptera's 2e Concept Car shows that it’s possible to design vehicles with exceptional aerodynamics, but like the XL1, EV1 and Insight, it compromises by having only 2 seats.

So the answer would seem to lie somewhere between the best attributes of both an Aixam MEGA and a VW XL1.  What characteristics and performance would such a vehicle have, if it existed?

●        It would be 350kg instead of 800kg.  E.U. Regulations define a Category L7e vehicle as being 350kg (and a maximum of 15kW power).  This weight limit would have the additional benefit that either the performance (or the fuel economy) would be better than the XL1, when going up steep hills or when accelerating.

●        The bodywork would be plastic instead of Carbon Fibre.  Although Quad-Bike vehicles do not require Compulsory Crash Testing, Aixam voluntarily submit their vehicles for Crash tests, and the vehicles pass with flying colours.  Safety would therefore not be compromised by using Recyclable Plastic for the main body, and the vehicle would be affordable and also could be marketed on the basis of its additional "Eco" credentials.

●        The vehicle would be a Series Hybrid.  Parallel Hybrids are a step too far for a small 350kg vehicle.  The reduced weight is also well within the capabilities of 15kW Electric Motors, so  the additional "boost" from connecting the Combustion Engine simply isn't  as essential.

●        The transmission would be a standard ICE drivetrain.  VW's XL1 Concept has a seven speed gearbox (and three clutches), in order to maximise the amount of time where the motors are at their most efficient.  The Aixam is at the opposite extreme: no gears.  A good compromise is to use a standard ICE Clutch and Gearbox.

●        The bodywork would have aerodynamics similar to or better than the XL1.  The Aixam MEGA's bodywork is modelled around the traditional "upright” passenger seating arrangement, to reduce the size of the vehicle.  The whole vehicle is designed for City Driving: attention to aerodynamics was therefore never a pressing concern.  However, for a long-range vehicle, 60mph is an absolute minimum speed, with 70mph and above being much preferred.

●        The vehicle would use "Eco" Low-Rolling Resistance Tyres. One of the disadvantages inherent in standard ICE and heavy EVs is that the harder "Eco" compound tyres wear out very fast, especially if driven at  high speeds.  A vehicle that is under 600kg including its passengers, that drives at sedate but acceptable speeds, would last a lot longer,  as well as take up very little energy (under 700 watts at 55mph) on rolling resistance.

●        The batteries would only be between 2 and 3 kWh.  With Hybrid Vehicles, large battery packs are inherently unnecessary, unless the vehicle is also a Plug-in Hybrid and is expected to operate for long periods as Pure Electric.  However: in order to minimise cost and weight, it’s reasonable to assume a minimalist battery, because the Hybrid can always continuously recharge, until the fuel runs out.

With those characteristics in mind, a Vehicle Simulator can be run to show the predicted performance under certain conditions.

Figure 1 shows  that a 550kg (laden weight) vehicle with a 15kW Electric Motor can hit 60mph in about 20 to 21 seconds, and can reach 70mph with an additional 5 seconds. For an E.U. Category L7E "Quad-bike" car, such performance is exceptional. The assumption that the aerodynamics are also at least as good if not better than the XL1 also means that the fuel economy is around 164mpg when cruising on flat roads at 60mph.

Further calculations show that the worst-case fuel economy conditions are under extreme conditions such as steep hills, but even here, the reduced weight of the vehicle comes into its own.

Figure 2 shows that the same vehicle needs 12kW to sustain 60mph on a 25% Gradient, which translates into a fuel economy figure of 70mpg. With great care and additional focus on efficiency savings right across the board, such as those carried out by Volkswagen, fuel efficiencies of 300mpg and above are achievable.  However, the Law of Diminishing Returns applies, as does the sheer practicality and social acceptability of the vehicles, as anyone familiar with Shell's Eco-Marathon can attest.

To summarise: the combined best characteristics of the Aixam MEGA and the Volkswagen XL1 with a Series Hybrid Drivetrain work well to produce exceptional fuel economy figures in a vehicle that is otherwise neither disruptive of expectations to manufacturers nor its owners, with the only major assumption being that a very low aerodynamic resistance target can in fact be met. 

However, many cars already prove that good aerodynamics are possible, such as the XL1, the GM EV1, Honda Insight and others such as the Automotive X-Prize Finalists (Aptera, Li-Ion Motors and Edison2). So, as the performance statistics of the X-Prize finalists also help to emphasise, it's technically possible to achieve exceptional fuel economy figures and also keep up with modern driving conditions.  This serves to underscore the original question: where are all the ultra-efficient Production Road Cars?

The Sherlock Holmes Approach

A little detective work is needed, to help solve the mystery.  Potential reasons why Ultra-efficient Production Road Cars cannot be bought include: 

●  The cost of manufacturing is too high.

●  The cost of parts is too high. 

●  There's a conspiracy by the Oil Companies.

●  There's a Government conspiracy.

●  Vehicle Manufacturers want to make higher profits.

●  Vehicle Manufacturers lie about the Fuel Economy figures. 

●  Vehicle Manufacturers take liberties with the figures. 

●  Potential Car Owners don't believe the reported Fuel Economy figures. 

●  Potential Car Owners don't care about the Environment. 

●  Potential Car Owners don't care about their wallets.

Many of these are plainly ridiculous; some are more subtle.  But before even getting there, a problem can be seen immediately with the last three possible reasons: chicken and egg.  It requires a very loyal Potential Car Owner to believe in a vehicle which they cannot test drive. It’s therefore necessary to add these additional circular reasons:

●  Vehicle Manufacturers won't commit to manufacturing without orders. 

●  Dealerships won't receive orders for vehicles that don't exist. 

●  Potential Car owners usually want to test drive a car before buying.

This issue of getting an entirely new and untested vehicle into mass-production through standard channels is particularly irksome.  Large Vehicle Manufacturers obsess over tiny fractions of the cost of parts, in order to maximise profits. They also are reluctant to commit tens of millions in any currency, in advance, to the tooling and factory costs, without knowing that the vehicle is going to be a success.  Whilst a few prototypes are made, they are made using techniques that are prohibitively expensive to scale up, even to supply just a few hundred cars across all dealerships, for test drive purposes.  The average Mass-Volume Manufacturer really is stuck between a rock and a hard place, in ways which the smaller manufacturer or the Kit-Car manufacturer is not. Thus, whilst small incremental changes to an existing proven tried-and-tested design, stretched out over years or decades is acceptable, a radical departure from all previous Sales Forecasts is too much, just in terms of setup costs if nothing else.

Regarding the cost of manufacturing: this is one of the problems associated with Research, and with Grant-funded Development.  Whilst there is significant focus on developing innovations that would reduce fuel consumption, there is not enough focus on actually getting those innovations into mass-production. The Automotive Industry as a whole is exceptionally conservative: even small but significant improvement made by a wholly-owned Subsidiary to an existing design is often completely ignored by the parent company, despite long-term cost savings or fuel efficiencies for the Car Owner that would make the vehicle more attractive to buy.

On the issue of parts: if any expensive non-mass-produced parts were selected, then it would be justifiable to claim that Ultra-efficient vehicles are not on roads today because of the cost of parts.  Examples of such vehicles include the infamous General Motors EV1, which had a 40kW Williams International Gas Turbine.

Many people forget that it is a legal requirement for Vehicle Manufacturers to supply parts for several years after a vehicle's production officially ceases, and the cost of manufacturing, storing and supplying those parts has to be factored into the cost of the vehicle.  If a Manufacturer cannot obtain a guaranteed supply of parts, they expose themselves to liability (cost). 

Many vehicles including some Airplanes have been forced to end production not because of reliability or other issues with the vehicle itself but because people forgot what a particular piece of factory machinery was being used for (or simply needed the space), and scrapped it, not realising that the machinery was critical and dedicated to making a particular part. So, just as Ford uses mass-produced parts in its high-performance "Special Vehicles" made by their SVA Team, it's unfortunate that it makes sense to keep the innovation to a minimum, or at least to use well-proven parts that can easily be obtained.  Even Toyota, with their highly desirable RAV4 EV, ran into difficulties fulfilling the last few orders because the model on which the innovative drivetrain was based had ceased mass-production: as a result, just like General Motors with the EV1, Toyota also began crushing leased RAV4-EV vehicles on return, until a public campaign persuaded them to stop.

The "Government Conspiracy" hypothesis also doesn't stack up.  Far from conspiring against the introduction of EVs, several Governments have worked ineptly to provide funds, incentives and often rolled out Laws requiring Vehicle Manufacturers to clean up their act.  The problem is that often these measures don't go far enough and, working with Corporations that deliberately drag their feet knowing and dreading the costs involved in getting the vehicle into mass-production as well as the ongoing spare parts support burden, these Initiatives sparkle and either fizzle out or have cold water quickly poured on them after the targets and goals of the Initiative have been met - often only one day after. In some ways, it might be concluded that Governments should know this, and should help fund an Initiative throughout its entire cycle. However, that would be assuming too much, and would also be hard to justify.

So the key is, therefore, that large mass-volume Vehicle Manufacturers are operating in a highly efficient and very important mode which helps ensure the long-term continued survival of the Corporation, into which it is unfortunately almost impossible to incorporate or include any innovation or deviation from that efficient path, even with access to vast resources bolstered by Government Grants and other financial Incentives. This problem is best described in the book "The Other Side of Innovation”.

In summary: even if mass-volume Vehicle Manufacturers were persuaded to make Ultra-efficient affordable "Green" Hybrid Electric Vehicle, the criteria required to do so are so far out of their comfort zone that the costs and financial risks associated with doing so scare them witless. So, purely out of self-preservation, they do everything they can to ensure that their exposure to liability and cost is contained or eliminated - even if that means destroying perfectly good vehicles.

This rather stark but perfectly logical explanation leaves people with the feeling, somehow, that a pair of wings might be a better investment than new set of wheels, as, barring a miracle or a break-through Scientific Discovery (with its own disruptive barrel of laughs to deal with), the upcoming Peak Oil "Cliff" at the end of our "Road to Planetary Ruin" results in its inevitable, quite probably messy but sadly avoidable consequences. The question becomes, therefore: if Ultra-efficient affordable Hybrid Electric Vehicles are technically perfectly well possible to make, today, but are too radically different for the normal mass-production Vehicle Companies to get involved with, how else can such vehicles be made available, before it's too late?