I think the new Prius C is indicative of Toyota having lost its hybrid way.

I write that with a rather heavy heart: anyone who has read my stuff over a long period will know that I previously embraced and relished hybrid technology.

The first hybrid I ever experienced, around the year 2000, was an NHW10 grey-market Japanese import Prius – it blew me away with its refinement, quality and fuel economy.

Back in 2003 I new-car-tested a hybrid Honda Insight – we did 3,500 kilometres in four days. The fuel economy? Just 3.6 litres/100km. The original Insight is the most fuel-efficient car ever sold in Australia.

In 2004 I tested an NHW20 Prius over 5,400 kilometres in seven days; I then called it one of the most fascinating cars you can buy.

As a magazine tester of new cars (a role I no longer play) I also drove two models of the Honda Civic Hybrid, and the hybrid Lexus GS450H, Lexus RX400h and Lexus 600hL.

I own a first gen Honda Insight, and for years I owned an NHW10 Prius that I first supercharged, and then turbocharged.

But I’m not wedded to hybrid technology.

My current main car is a mildly-modified 2008 Skoda Roomster 1.9 turbo diesel. It gets fuel economy in my use that varies from the high-fours (in litres/100km) to about 6 litres/100km. And that from a relatively old and low-tech diesel design.

I haven’t driven the current model Prius, but I’ve experienced a Camry Hybrid- and wasn’t much impressed. The fuel economy wasn’t outstanding, and the car drove with an uninspiring feel.

But with the release of the Prius C, I thought that things might be very different.

The lightest (1120kg) and cheapest (AUD$23,990) hybrid Toyota sold in Australia, the Prius C has an official fuel economy rating of 3.9 litres/100km. That’s the same as its big brother Prius – but surely that must be a quirk of the testing system… with the C’s smaller size and mass, and lower total power, surely there’d be a benefit to real-world fuel economy?

And boasting a host of advanced technologies – including a new inverter, motor and battery – you’d expect that this to be as good in fuel economy as a hybrid Toyota gets.

Well that might be the case – but unfortunately, these days, it just isn’t good enough.

Today I visited a Toyota dealership. It wasn’t with just prurient intent: if the car did what it was supposed to, I was quite prepared to buy one.

The presented i-Tech model (a higher trim level that costs $26,990) was OK inside, although definitely nothing outstanding. The interior room was alright (a tall adult could sit [j-u-s-t] behind a tall driver); the digital instruments were clear; the seats comfortable; the load area pretty small (and the rear seats fold to give a pronounced step in the floor); and the double-DIN upgrade nav looks like it should cost only about $400 through eBay.

But hey, it’s a small car that isn’t priced at luxury levels.

On the road, with three adults and a seven-year-old in the car, the transmission refinement was good, the steering welcomingly much heavier in feel than previous Toyota (and Lexus) hybrids, and the power was – well, a bit disappointing. The last Prius I drove, now an old-model NHW20, could on green lights wheelspin its way across intersections – the current Prius C had not remotely enough low-down torque to do that. But, again, it was OK – but definitely not scintillating.

But the fuel economy? Oh dear.

In a gentle drive, about a third through urban conditions and the rest on 80 and 100 km/h freeways, the car massively disappointed. It started off at about 6 – 7 litres/100 (not a problem; it was a cold start) and then gradually dropped to about the mid-Fives. With the ultra-economy mode then engaged, it continued to drop – reaching a low of 4.6 litres/100 and then rising finally for a trip average of 4.7 litres/100 for the 20-odd kilometres.

Well, isn’t 4.7 litres/100 really good?

Only if you have no better comparisons…

My 1999 (read that again – 1999, that’s 13-year-old technology!) Honda Insight in similar conditions would, I’d guess, be in the mid-Threes – but that’s in a car that is much smaller (only two seats) and is also much lighter. So in many respects it’s not a fair comparison.

But what about my Skoda Roomster? It weighs about 200kg more than the Prius C, has much better performance, vastly more interior space – and like the Prius C, has 5-star crash test safety.

Since we’d taken the Roomster to the dealer, I immediately drove exactly the same road loop just undertaken in the Prius C. We didn’t have the salesman aboard, but apart from that, the conditions were as identical as it was possible to make them – same speeds, same roads, same traffic.

And the fuel economy of the Roomster? It came in at 4.9 litres/100km.

Seeing those figures: 4.7 for the cutting edge, small, 2012-model hybrid Prius C, and 4.9 for the much larger, old fashioned 2008-model diesel Roomster, suggests to me that in the real world, plenty of current small diesels will match the fuel economy of the Prius C.

For me, the Prius C could not be justified in any way as a replacement for my existing car – the Roomster.

And so then you wonder – for whom would the Prius C be justifiable over other fuel-efficient cars? After all, why buy a car that is demonstrably far more complex, and has a battery pack that will one day fail, when the raison d’etre of the hybrid – fuel economy – is no longer stunningly better than the others?

The above statement really indicates that Toyota has lost its way: that the hugely innovative and technologically incredibly brave step that occurred with the release of the NHW10 Prius at the end of 1997, the move that saw car makers the world-over stare in disbelief and then turn towards hybrids – well, that technology is now more about selling cars on a gimmick rather than through demonstrable real-world advantage.

What a bloody shame.

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If you’ve been sawing, grinding or filing metal, it’s likely that you’ve ended-up with a nose full of it. Not just snot – but black snot.

For years I thought it a just curiosity that resulted from that pursuit.

But now I am rather wary of it.

Recently, after spending a full day cutting and grinding, I started feeling a bit ill. The next day, going back to doing some more cutting and grinding, I wore a light dust mask.

But that night I still had black snot – and a hacking cough.

After a few days of feeling crap, I went to the doctor. I hate going to the doctor, but this one had the advantage of being the most beautiful doctor I’ve ever been to. And what did she say? You’ve got a virus – harden up.

But despite that opinion, I really do wonder if the metal dust that I’d been getting into my lungs didn’t have something to do with it.

Now when cutting and grinding, I wear a half-face respirator that has two double filters, one to catch particulate matter and the other for fumes. The result? No black snot – and filters that after only a few days of work, have changed from white to black.

Better caught in the filter media than in my lungs – or in my snot.

Beware that black snot….

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In the story on suspension design that was published in AutoSpeed today, I said:

One standard model of car that I often see has a clear pitch problem: once you recognise its behaviour, you can see these cars porpoising along on all sorts of road surfaces! (No wonder I felt ill when I rode in the back of one.)

For those of you who live in Australia, that car is the current VE Commodore.

When you are driving in a lane adjacent to a VE Commodore, and especially when you can see it from the rear three-quarters perspective, carefully watch its body behaviour.

What you will see is dramatic pitching over bumps.

Rather than the car as a whole moving up and downwards on its suspension as the bump is met and absorbed, the back rises and falls, and the front rises and falls – and when the back is up, the front is down, and when the back is down, the front is up!

It is fascinating watching a VE pitch, and then watch another car pass over just the same bump and barely pitch at all.

I reckon that Holden suspension designers have completely forgotten this aspect of suspension design – if of course they even knew of it in the first place.

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It’s not every day that you can be part of a new suspension system development.

And wouldn’t you give five or ten bucks to make it happen?

Video on the development

Donations

Back here I described my search for the lightest possible springs for a lightweight human-powered vehicle. Although I didn’t say so at the time, it had been my desire to use rubber – light, cheap and readily available.

However, as that article describes, I found it impossible to find a rubber (or elastomer) approach that allowed high spring deflections without overstressing the rubber. High suspension deflections were possible with rubber, but in turn that required high motion ratios (ie leverage) that resulted in large stresses in the suspension arms and spring seats.

However, since writing that article in 2007, I have been reading everything I can find on using rubber as suspension springs – and I have to tell you, there’s not a lot around.

But today I found a paper that I think is worth sharing with you. I can’t share the content – it’s copyright – but I can say it’s the best treatment of using rubber as vehicle springs that I have seen. It was published in 1956 and the author is Alex Moulton, the man who later developed the rubber springing used in the Mini, and the rubber-and-fluid suspension used in the Mini, Austin 1800, Morris 1100 and other vehicles.

You can buy the paper from the Institution of Mechanical Engineers Proceedings Archive here – it will cost you US$30.

If you are interested in lightweight vehicles with sophisticated suspension design, I think it’s a must-read.

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It’s interesting how things change. When I first started writing on the Web about cars, one area of modification concerned me a great deal – hot chips. No, not the sort you eat, but the sort that reorganise the engine management’s programming. In short, many of the chips for which people handed over lots of money simply did not work.

Back then, in the late 1990s, even the best people working in that area were simply making semi-random changes to code and then seeing what happened. The type of software available these days for many cracked factory engine management systems, where full maps are able to be viewed and tweaked in plain English, just didn’t exist. (The notable exception was Kalmaker for GM systems – literally a decade ahead of its time.)

So customers were handing over hundreds and hundreds of dollars for products that were often of no benefit. Some chip cookers retarded the mid-range timing before returning it to standard at the top end: that gave a sudden rush of power that convinced customers their cars were now going harder. Others started with a car that had been tweaked to perform worse than standard – and then fitted the original chip, so resulting in a ‘gain’. 

But when solutions for factory management problems were hard to find, and when the alternative comprised expensive, aftermarket, fully programmable engine management, chip cookers still did good business. Some were better than others: all to my mind were working way too much in the dark.

Here at AutoSpeed we sought to reveal some of what was going on by doing interviews with chip companies – interviews with Powerchip’s Wayne Besanko and also with ChipTorque’s Lachlan Riddel. Lachlan Riddel acquitted himself better in the interviews – and also had (and has) a much higher degree of technical knowledge than Wayne Besanko – but this exchange with Riddel is symptomatic of the level of knowledge that then existed in working out what parts of the code to change in order to gain a certain outcome:

AutoSpeed: A rather cruel analogy of this process [of modifying the software] is that you’re in a dark room with a large animal. You can’t see the animal, but you’re equipped with a pin. It seems to me to be an extraordinarily random way of going about learning how something – with perhaps 5000 variables – by dragging one up at a time and seeing what happens. You’re pricking the elephant in that dark room – but whether you’ve got his nose, or whether his eye you don’t know….. He yells each time – analogous to the fuel getting richer each time – but you don’t really know why the fuel gets richer. You don’t know where you’re poking the pin….

Lachlan Riddel: I appreciate the analogy….. I’ll be honest and say that off the top of my head, I can’t quickly give you a better one that more describes the process that I use. (But) if I felt as blind as the analogy that you have described, I wouldn’t start the job.

In the interview with Wayne Besanko we found that the level of technical knowledge being brought to bear was minimal; some readers may have concluded that buying a Powerchip was not for them.

However, those interviews were carried out in 1999 and 2000 – a very long time ago. In the years since, the range of software tools available to tuners has massively improved. In fact, it’s not exaggerating to say that these days the software available to allow reprogramming of many (but not all) factory management systems allows better control of outcomes than the best programmable aftermarket systems could (and can) achieve.

So when I lived on the Gold Coast and ChipTorque was nearby, I was happy to ask the company to tune the modified EF Falcon six cylinder we developed as a cheap and cheerful AutoSpeed project car. The company knowledge, the software that was available to do the tuning and the achieved results all matched my expectations.

And when, just this month, I wanted my turbo diesel Skoda Roomster remapped (it runs the VW 1.9 PD engine), I was happy to approach Powerchip. The car’s modifications will be covered in detail this coming year in a full AutoSpeed series, but the results achieved by Powerchip’s Bill Ingram, working on the Queanbeyan dyno of ESP Racing with Glen Kelly driving, were outstanding.

Together with the intake and exhaust mods already undertaken, the Roomster remap has improved power and fuel economy while retaining absolutely factory driveability. I am amazed at just how good the outcome is – I rather expected a stutter or two, or black smoke, or at least some downside. But I cannot find a single tuning negative.  In this case the tuning software was extremely effective – and I might add that I was able to watch every tuning step being undertaken, and ask Bill (and have answered) whatever questions I wished.

Two points from all this.

Have things got better in terms of tuning cars? Yes, by a simply massive amount.

And should people assume that interviews that are more than a decade old reflect current company abilities? Well, that would be a pretty dumb thing to do…

The ability of a wheel to move backwards when it hits a bump is a very important ingredient in gaining good ride quality. The movement is accomplished in car suspension systems by the use of rubber bushes; many have asymmetrical voids within them to allow this type of tiny backwards movement without adversely impacting on bush stiffness in other directions.

But what about in a machine that requires suspension pivot points that can’t cater for this movement, ie those that need non-flexible pivots?

In a two wheel machine, especially one that is very light in weight, a leading arm suspension can be designed that will achieve this.

Leading arm suspension systems have been used in commercially produced motorcycles (eg the Earles forks) utilised by BMW in the 1950s, and shown here.  Note that the springs/dampers do not locate the suspension in any way, instead, the leading arms (green arrow) are pivoted at the point shown by the red arrow. The “forks” are indicated by the blue arrow and the springs/dampers by the black arrow.

A leading arm design of this type has anti-dive under brakes built in; as the braked wheel tries to keep turning, it pushes up on the pivot point, so counteracting the weight transfer forwards. In fact, some Earles machines are known to rise at the front under brakes.

But how does this front suspension design allow a movement backwards when the wheel hits a bump? As shown in the BMW design, it doesn’t – or at least, not much.

But as shown in the design of this bike, it does. Again the green arrow points to the leading arms, the red arrow to the pivot point, the blue arrow to the spring/damper and the black arrow to the forks. Note how the pivot point is low and so the wheel clearly moves backwards as it rises.

The bike is a Birdy folding machine and the front suspension travel is only about 15-20mm. I recently bought one and I am amazed at how well the front suspension works, especially given its minimal travel. It’s not effective over large bumps but it works brilliantly at removing vibration and harshness.

It’s also a particularly interesting design because in many suspension types, building-in anti-dive geometry actually causes the wheel to move forward as it moves upward, so making bump absorption worse rather than better. That’s not the case with this design.

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Recently I read Thrust, the book by Richard Noble on his life in breaking land speed records, culminating in the development of the ThrustSSC car – the current world land speed record holder. The record was achieved in 1997.

The book is outstanding on a number of levels, including its honesty and clarity. The section where driver Any Green describes his techniques for steering the car is just amazing, as is the constant battle for funds that occurred every day of the project.

But one small part of the book particularly interested me: the section where the primary designer Ron Ayers describes how he went about designing the car.

The text is reproduced here:

How do you start designing a vehicle that is totally unique? Here are the characteristics of the problem that faced us:

1. By travelling supersonically on land we would be exploring a region where no-one had ventured, where even the problems could only be guessed at, so there were no known solutions.

2. As the aerodynamic forces involved were so enormous, any accident was likely to be fatal.

3. The project would always be underfunded, short of people and time.

4. There would be only one chance. The final car was also the first prototype. The first lines drawn on paper could well be the ones that are made. The very first assumptions and decisions, if incorrect, could put the project on the wrong track and there would be no chance of starting again.

Problem: how do you make those crucial first decisions when so much is uncertain?

First, every decision had to be a robust one. That meant it couldn’t be invalidated by subsequent decisions.

Second, we could only use technology we were very confident with. This militated against using the very latest technology in some cases.

Third, although direct experience of supersonic travel on land did not exist, we consulted widely, with aviation and automobile experts in industry, universities and research establishments. Experience with Thrust2 was invaluable, particularly in pinpoint¬ing practical and environmental problems that might otherwise be overlooked.

Fourth, where possible we left room for adjust¬ment or change, so we could incorporate knowledge acquired subsequently. Nothing was “hard wired”. One reason for using a steel chassis was that it could be modified if necessary.

Fifth, we didn’t try too hard to integrate the systems. If we needed to change one of them, we didn’t want to be forced to change them all.

Sixth, our choice of a twin-engined car made the design massively overpowered. Thus weight was not a critical factor.

The design resulting from such an approach must necessarily be “sub-optimum”. A second attempt, incorporating the lessons learned, would undoubtedly be better. But the design was proved in practice, and there was little about the basic concept that would need to be changed.

The more you read those notes, the more you realise the clarity of thought being employed: it’s also food for thought for anyone building a unique design of anything.

Noble and Green are currently involved with another land speed record car bid – the Bloodhound SSC.

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The trouble with suspension roll centres is that they’re often rather obscure in concept, let alone in location.

In this article I tried to simplify the concept of roll centres, largely by using geometric drawings.

(So what actually is a roll centre? It’s the imaginary point about which the car rolls. The front and rear suspension roll centres can be at different heights above the ground [but always on the centreline of the car] and on different vehicles the heights can vary from being above the ground, to at ground level, to below the ground.)

Normally roll centres are located by careful drawings of the suspension, a prerequisite being that you need to know the exact location of suspension pivot points, lengths of suspension arms and so on.

However, as shown in this diagram, the roll centre of an existing vehicle can be located by directly measuring the way the car behaves. If the car is physically rolled from side to side, there will be one point that never moves (or moves only minimally). That’s the roll centre. If multiple photos are taken of the car in end-view, this point can be easily located. 

This is a very useful technique – you can locate the roll centres for either the front or rear suspension, and no difficult measurements of the suspension geometry need be made.

And it’s not just the roll centre(s) that can be located in this way. In addition to roll, cars pitch – that is, the front dives and the rear rises, or vice versa. This occurs not only under acceleration and braking, but also over bumps in the road. The amount of pitch – or, more precisely, the pitch accelerations – are a major determinant of ride quality.

So how do you find the pitch centre? A book I have – Fundamentals of Vehicle Dynamics by Thomas Gillespie – devotes a number of pages of mathematics to locating the pitch centre of a car. However, as with the roll centre, pitch centres can be found by direct measurement.

I did this the other day for my recumbent, pedal, suspension trike. I am doing a lot of work on its suspension, including measuring real-time pitch accelerations over bumpy surfaces. After making a host of measurements of these accelerations, I thought I should find where the pitch centre actually is.

I had two photos taken of the trike (with me on it), both in side view. In one pic, the front suspension was at max extension and the rear in max compression. In the other pic, the suspension extensions were the other way around. (I use air suspension and for this test I interconnected the units front to back, so giving zero resistance to pitch. To get the front to adopt max compression, I added some weights.)

I then overlaid the pics, playing with the image until I could find a point around which the trike body was rotating in pitch. This was best shown by placing radii centred on that point – the circular lines intersect with the same part of the trike in both pitch extremes. (It’s harder to explain than it is to do!)

In this pic, the pink dot is the pitch centre. As can be seen, the greatest mass on the machine (that’s me) is located above the pitch centre. Furthermore, a lot of that mass is located a fair way from the pitch centre, increasing the pitch moment of inertia. This is one reason that over rough ground, the pitch accelerations of the machine are very low.

Talking about moments of inertia in pitch is taking it a further step in complexity. But back to ‘centres’ –  if you’re grappling with the suspension design of a custom vehicle, it make things a lot clearer when you can so easily locate not only the roll centres, but also the pitch centre.

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