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Prius vs Insight

Both hybrids and both Japanese but otherwise very different

by Julian Edgar

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Although in Japan the Honda Insight and Toyota Prius were developed simultaneously and released at similar times, and although both are hybrid battery/petrol hybrids, they are very different cars. Not only are the specs different (mass, petrol power, electric power and battery capacity) but the philosophies are also quite divergent.

Both can now be bought locally from around AUD$20,000.

I own both an Australian-delivered Honda Insight and a Japanese-market NHW10 Japanese-delivered Prius. Like all Australian-delivered Insights, the car uses a 5-speed manual transmission. Like all Prius models, my NHW10 uses the very trick variable transmission that integrates two electric motor/generators. On the other hand, the Insight simply uses a 10kW electric motor sandwiched between the engine and gearbox, permanently attached to the end of the engine crankshaft.

More Mature

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In short, the Prius represents a far more mature approach. Clearly, Toyota spent vastly more in developing the Prius than Honda did the Insight - and this shows in every area of the car. The Prius is astonishingly complex and accomplished – an amazing combination to achieve from Day 1 of a new technology. The integration of the powerful electric motor (30kW on this first model) with the engine via the Power Split Device makes the seamless mixing of petrol and electric power a daily reality. The Prius always feels torquey and strong at low speeds, despite its high 1250kg weight and lack of outright power. Although reverse gear uses only electric power (the petrol engine cannot drive the car in reverse) it can still quietly torque its way up my steep driveway. On the open road, engine revs automatically vary with load: you know you’re climbing a steep hill because engine revs rise. But all the driver needs do is put their foot on the throttle – the incredibly complex electronic and mechanical controls do the rest.

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Inside, the Prius is roomy and well packaged. There’s adult space in the front and rear and the boot is reasonably sized (although in this first model not very long). The ride is soft and comfortable and the seats well matched to the spring rates. The colour LCD in the middle of the dash is Soarer-sophisticated and the controls all work with typically Toyota quality and ease.

However, the handling is poor and the steering dreadful, being vague and over-assisted around centre.

Take a look under the skin of the Prius and the engineering thoroughness is formidable. I’ve had my car in lots of pieces (it’s been supercharged and then subsequently turbocharged) and I also bought a front cut which I disassembled. Everything – and I mean everything – is superbly made and engineered. The high voltage connectors, the filtered fan-forced cooling of the battery box, the water cooling of the power converter under the bonnet, the use of standard Toyota hydraulic trans fluid in the Power Split Device. Even the use of only a slightly modified Echo 1.5-litre VVTi engine means that this was always a car that Toyota expected to work well over the long term – the engine was a known quantity. The book The Car That Shook the World gives some idea of the thoroughness with which Toyota approached the task, to the extent that for example Panasonic had to change the way that they made Nickel Metal Hydride batteries to meet Toyota’s durability expectations.

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The Insight is very different. Perhaps the biggest difference is in the body. Rather than optimising a very sophisticated driveline to gain the huge economy advantage the Prius had (and has) over conventional petrol engine cars, Honda decided to go for a more basic driveline and get the gains mostly from the body. The result was an all-aluminium design with a very low drag co-efficient. A low drag number is no good if the frontal area of the car is high so Honda decided the Insight would be a small, low car. The body-in-white weighed about half as much as a contemporary Civic and yet was stiffer in both bending and torsion, and was also safe in a crash.

VTEC Engine

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Honda had used its expertise with the aluminium NSX to build the Insight body and in the same vein decided to draw on their undoubted engineering excellence to build a very fuel-efficient engine. The unique 1-litre 3-cylinder uses VTEC valve timing, lightweight components (eg a magnesium sump) and low friction technologies to make it probably the most economical, lightest 1-litre engine in the world. (And a far cry from a slightly modified Echo engine!)

Toyota decided that the driver should be untaxed by driving a Prius; Honda decided that the driver would be very much involved in driving a manual transmission Insight. And it’s not just the fact that there’s a gear lever in the cabin; the Honda is simply a far harder car to drive well. Partly it’s the extraordinarily high gearing (both fourth and fifth are overdrives, and second gear easily takes you to 100 km/h) but it’s also the way in which Honda has designed the car to trickle along at 1200 or 1300 rpm in fifth (top) gear, using little fuel but feeling a fraction awkward to the attuned driver. And of course, if you meet any sort of rise in that gear and at those speeds, you’ll need to be rapid on the down-change – not just to fourth but sometimes to third or even second!

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Driving through a hilly urban area it’s easy to be embarrassed by the Insight; in a Prius you just put your foot down a little harder and let the torque do the rest.

The electric assist in the Insight (it automatically adds its torque with throttle movement) is effective, but if you’re used to driving a Prius, it’s not very strong. Regen braking is also used in both cars but in the Insight it’s most prevalent when you’re also engine braking – you cannot regen brake without engine braking because as soon as you push in the clutch, drive torque to the electric motor is lost. In the Prius you can regen to a near standstill. Both cars switch off the petrol engine when you’re stopped (and then very rapidly restart it as needed) and this system is equally effective in both models.

Packaging

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In some respects the Insight is incredibly poorly packaged. The two seats are roomy in all directions – headroom, foot-room and elbow room. You sit very low (an especial contrast to the Prius which has a high hip point) but considering the size of the car, it’s all quite spacious. So where’s the problem? It’s in the load area. Incredibly, almost all the load area under the hatch is taken up by the battery/electronics box. The box is positioned forward (on top of the fuel tank which is also ahead of the rear axle) leaving room for a shallow lidded compartment directly behind it. But the bizarre thing is that when you remove the carpet (as you do to access the spare wheel) you can see space needlessly taken up with foam fillers and aluminium cover plates. Without any difficulty, the volume of the lidded bin could have been increased by 40 per cent...

Perhaps luggage space was deliberately limited by another oddity – the Insight has an extraordinarily small load carrying capacity. In Australian Design Rules form the Insight is listed as having a maximum vehicle weight of 1015kg. With a car mass of ~850kg, that leaves just 165kg for two people and their luggage! If you’re carrying two 80kg people, there’s load carrying capacity for one very lightweight small bag... It’s all very odd, especially when you realise the rear suspension travel and spring rate were clearly designed with this in mind. Place a large car battery in the boot and you can feel the rear suspension bottom-out over every speed hump.

On the other hand the Prius is just like a normal car – put four people and some luggage in it and it certainly rides low... but it copes.

Modifications?

If you’re interested in modifying a hybrid, then Insight is definitely the one to pick. Because the Prius transmits its power through a planetary gearbox that uses the electric motors to retard certain parts of the transmission, the power that can actually get to the wheels is limited. With an engine power increase, the trans doesn’t die, but any extra engine power goes to charging the high voltage battery, rather than making the wheels push the road back harder. The Prius is also a very difficult car on which to change the air/fuel ratio; in standard form it stays at 14.7:1 at all loads.

On the other hand, the Insight driveline can be regarded as completely conventional, but with an added electric motor. All the normal modifications should be able to be made to the Insight engine with no more problems than to any other VTEC Honda – and there’s a lot of room at the back of the engine to mount a turbo...

Fun

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The Insight is vastly more fun than the Prius to drive. The steering (electric assist rack and pinion like the Prius) is precise and well weighted, the handling (although nothing outstanding in its own right) is better than the Prius, and the gearlever throw short. And of course, the Insight is a VTEC Honda... While the gearchange ‘up’ and ‘down’ suggestion lights on the dash constantly implore up-changes (so the engine speed is reduced, the throttle opening larger and the electric assist can do some of the work), if you ignore the dash lights and rev the Insight to its 6200 rpm cut-out, you’ll find a sweet and willing three-cylinder that, in the final analysis, gives much better performance than the NHW10 Prius.

The stopwatch shows that, but of the two, the Prius always feels more effortless, except at high speed.

And as well as being more effortless, the Prius is far quieter. Whether it’s because of the aluminium body or that the weight goals set by Honda didn’t include soundproofing, the Insight’s body is quite noisy. Road noise, body resonances and tyre noise all intrude. (The engine is comparatively subdued.) The Prius feels like a small Lexus – and is much smoother and quieter than a contemporary or even current Corolla – but the Insight feels much closer to a budget Korean shopping trolley.

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But the Insight has trick up its sleeve, and it’s a damn good trick. Simply, the Insight delivers quite incredible fuel economy – consistently more than 25 per cent better than the Prius! It’s quite possible to achieve 3.5 litres/100km driving the Insight on the open road at the 110 km/h speed limit with no economy driving measures being taken at all, and my Insight has achieved a lifetime fuel economy of 4.6 litres/100km over its first 50,000 kilometres. I expect to easily better that in my driving; at the time of writing I have never seen a higher average than 4 litres/100km in any driving conditions.

(When talk turns to hybrid economy, people love bringing up diesels. And while diesels can be very economical, the figures often aren’t anywhere near what people are inclined to believe. As I write this, I have on test a 2-litre Peugeot 307 diesel wagon. Over its first 3000km it’s achieved 7.4 litres/100km and in my driving is getting 6.9 litres/1000. On a measured freeway drive it used 46 per cent more fuel than the Insight....)

Outcomes

So the reasons for the huge success of the Prius (especially in the US) and the relative lack of success of the Insight are clear. The Prius is a practical, easy to drive car that has a clear fuel economy advantage over pretty well all other petrol engine cars of a similar size, and also in the vast majority of conditions, diesel powered cars of a similar size. The handling and steering are nothing flash, but neither are they horrifically bad. It’s is quiet, smooth and comfortable.

The Insight is a car that appeals to a far narrower group. It’s both sporty to drive and can be a lot of fun, but when driven for economy is a much harder ask than the Prius. Its load carrying ability is a joke but for two people (and no luggage) it works well. It can also turn in the best fuel economy of any car in the world but has quite respectable small car performance when the driver really wants to go for it.

In fact, apart from both being Japanese and both being hybrids, there’s almost nothing about the two cars that’s similar.

The Ultimate?

Toyota and Honda have chosen to continue to follow their divergent hybrid technology paths. Honda has dropped the alloy bespoke body but has stayed with the electric assist in a range of cars, while Toyota has continued with the Prius but has also introduced similar hybrid technology to other models.

But what would have been the result if, back in the late Nineties, Honda and Toyota had got together to build a hybrid car, just as now erstwhile enemies GM, DaimlerChrysler and BMW have developed the ‘two-mode’ hybrid driveline?

A Honda/Toyota hybrid would potentially have been a fabulous car – say a 1.5 litre VTEC four cylinder working with a Power Split Device in an all-aluminium Prius. The transmission could have had optional manual control of the selected gear ratio, in the same way Audi have a pseudo manual control mode on their CVT trans. Take a few hundred kilograms out of the Prius – especially if we alter the time travel even further to make it the current Prius – and you’d be talking a car with a 0-100 in the Eights – and obviously when not using that performance, even better fuel economy than is currently achieved.

Compared...

Model Specs

Prius NHW10

Prius NHW11

Prius NHW20

Honda Insight

Engine Power (kW)

43

53

57

56

Electric Power

(kW)

30

33

50

10

Vehicle Mass (kg)

1240

1220

1250

817*

Mass/power (kg/kW)

17

14

12

12

0-100 km/h (seconds)

16

13

10

11

Typical on-road fuel economy (litres/100km)

5.7

5.2

4.7

3.6

Subjective

Handling (/10)

5

6

7

7

Steering (/10)

6

6

6

9

Ride (/10)

7

7

7

5

NVH (/10)

8

8

9

6

Interior Packaging (/10)

7

7.5

9

5

Interior Features (/10)

7

8

8 or 9**

6

* quoted mass varies with market

**depends on trim level

Buying a Prius

When buying a Prius in Australia make sure that you know what you’re getting. The two earlier models – NHW10 and NHW11 – look very similar, but the NHW10 was not sold new in Australia (ie it’s a grey market car) and so parts are harder to get and it’s nearly impossible to diagnose faults – Toyota Australia dealers cannot do so as they don’t have the required equipment for this model. Furthermore, there were significant upgrades made for the NHW11 and so it is the better buy (but, as you’d expect, it’s more expensive). Japanese writing on any of the centre dash pushbuttons is an immediate giveaway that it’s a NHW10. The current model NHW20 is a much better car again.

See Prius Progression for a further breakdown of the models.

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