IS THE WORLD'S BEST-SELLING HYBRID STILL KING-OF-THE-HEAP FOR REAL-WORLD FUEL ECONOMY, OR CAN A SUPER-EFFICIENT LIGHTWEIGHT DIESEL KNOCK IT OFF ITS PERCH?
Both launched in Australia in the same week, both claim the thirst of a hermit monk, and both appeal in entirely different ways.
Both look… well, different. One brimming with idiosyncratic quirky Gallic charm – the C4 Cactus – the other, the new Toyota Prius, a riot of unusual lines but that drives as sensibly as a Bishop.
Citroen C4 Cactus ($29,990 +ORC or $33,827 on-road)
Toyota Prius ($34,990 or $38,987 on-road)
There is a $5000 gap in the purchase price, the C4 Cactus diesel the winner here at $33,827 on road (give or take a few dollars difference between states); the entry Prius at $38,987 on road.
The Citroen however is a small hatchback pumped up to look like an SUV. Its strategy to achieve low fuel consumption rests on stripping back weight and employing a ‘bare essentials’ 1.6-litre turbo-diesel.
It gets push-out rear windows, among other curiosities, to help it tip the scales at only 1055kg.
By contrast, the fourth-generation Toyota is a medium-sized four-door liftback, as it has always been.
Its strategy is to first add weight via a complex ‘hybrid synergy drive’ system utilising batteries and electric motor, to then use those assets to store otherwise lost braking energy and help take the load off the 1.8-litre petrol engine.
Kerb weight? A portly 1400kg in this up-spec i-Tech version (which adds $8000 to the base price).
Both vehicles drive the front wheels, and for all their differences, both achieve around the same performance – no official figures for Prius, but the C4 Cactus claims 0-100km/h in 11.4s.
Both also achieve roughly the same consumption. In official regulatory testing emulating mixed road conditions, the Toyota uses 3.4 l/100km, a drop of 0.5 l/100km compared with the previous model, where the brand new Citroen consumes 3.6 l/100km.
The figures for the ‘urban’ cycle are similarly abstemious: the C4 Cactus claims to use 3.9 l/100km where its rival is unchanged from its combined figure.
Turn to extra-urban testing – the claimed ‘highway cycle’ – and the Prius comes up with 3.5 l/100km, matching its rival.
But are these numbers pure fantasy when drivers get among traffic, hills, highways and bumps?
Today our aim is to cut through the controlled conditions of the laboratory claims and get some real-world figures. Which of these two cars, we want to know, is the supercar of economy?
THE TEST LOOP
Part 1: The ‘city cycle’
Under the Sydney Harbour Bridge was chosen as the startline for this economy showdown: the ‘harbour city’ can claim, without doubt, the most intense traffic.
With the 43-litre fuel tank of the Prius and 50-litre fuel tank of the C4 Cactus each brimmed to the top with 91RON regular unleaded and diesel respectively, we set off for the first 50km of purely urban testing.
This had us looping from the northern side of the Sydney CBD, directly to the south side. From there it was due west to drive the full 20km of the notorious Parramatta Road, a good portion of which acts as the single main arterial connecting New South Wales’ largest and second-largest (Parramatta) business districts.
A late afternoon departure had us emulating the frustrations of the daily commute.
In the heart of the western suburbs, the final 15km of this city-cycle drive had us weaving through the backstreets of Granville, Merrylands and Greystanes – the kind of driving you might do on a suburban shopping centre run.
Part 2: The ‘highway cycle’
The second 50km leg saw us join the M4 Motorway at Greystanes and travel a further 25km west to Penrith at the foot of the Blue Mountains, before performing a U-turn and returning.
The entire stretch is relatively flat with a 100km/h to 110km/h speed limit.
For control consistency, both vehicles had air-conditioning set to low (both fan and temperature) throughout the 100km trip.
The Prius was driven in ECO mode, while the C4 Cactus had its engine stop/start facility left on. Both drivers retained as tight a ‘convoy formation’ as possible, but with sufficient separation to avoid any slip-stream benefit, and moved on steady-state throttle throughout. Cruise control was avoided due to its compromises on efficiency.
Each trip computer was assessed at the halfway mark, and at the end mark. At the conclusion of the 100km loop, these readings were re-assessed comparing distance covered against fuel ‘top-up’ measurements.
So, rules and regulations sorted, and creating as controlled an environment as was practicably possible, let’s toss the laboratory results aside and see how we went in a real-world test…
Sitting on the start line under the Sydney Harbour Bridge, the Citroen C4 Cactus claimed a driving range of 900km; the Toyota Prius 920km.
But soon after beginning the slow slog through the Sydney CBD and there is already a problem emerging with the C4 Cactus.
Certainly its light and lovely steering, pleasant ride on 17-inch GoodYear Eco tyres – the same diameter as the Prius i-Tech – and the surprisingly refined diesel engine are nothing to complain about.
However, the intense traffic through multiple traffic lights meant the fuel-saving stop-start facility – which stops the engine when the brake is applied at the lights – had stopped working.
The battery it relies on to power the electrics of the car had already become overworked in cranking the engine multiple times in a short period of time. This is normal in cars with stop-start, we should note.
Meanwhile the engine is running and the trip computer rising – 7.3, 7.4, 7.5 l/100km…
No such issues in the Prius. The diesel Citroen may be refined, but it’s tough to beat the Toyota’s silence. This fourth-generation hybrid feels wonderfully grown up in its quick steering and nice ride comfort, if not its homely looks.
Its dedicated EV-mode works accelerating up to 57 km/h and accepts greater throttle input before firing the petrol engine compared with the previous model.
A batch of nickel-metal hydride batteries slung low in the chassis between the rear wheels means the Prius doesn’t have to rely on the single battery under its bonnet like its rival does. That battery pack is heavy, but powerful enough to keep air-conditioning running when the engine is off – unlike the Citroen.
However, we were not travelling fast enough to get the benefit of the energy recovery from braking. The Prius uses braking energy to charge its batteries, but in this kind of city driving it needed to occasionally kick its petrol engine into life to keep the batteries from running low.
The smooth hum of the hybrid powertrain, boasting a fluent continuously variable transmission (CVT) with essentially a single sliding gear, is in direct contrast to the lumpy changes of the diesel’s six-speed automated manual.
It is essentially a small, light, manual gearbox but with a computer that controls the clutch and gearchange.
Through school zones and an agonising Parramatta Road, it took an astonishing two-and-a-half hours to cover 50km at an average of 20km/h for both vehicles.
But this took us to the end of the urban loop. Here, the Toyota’s trip computer was showing 4.5 l/100km; the Citroen’s having settled at 6.0 l/100km once out of the gridlocked CBD.
Time, then, to turn onto the freeway.
Relaxed in sixth gear – although it doesn’t have a tachometer – the C4 Cactus is a surprisingly refined and smooth drive. In a drive without disruption, other than an errant truck in our face for a short part of the drive, we averaged 89km/h with the trip computer showing 3.9 l/100km.
The Prius had a clearer run (sans the truck that divided the two cars), and recorded a 94km/h average speed on this leg for a 4.1 l/100km consumption average.
With steady-state throttle used at higher speed and little braking required, the Prius however needed to rely more on its petrol engine and couldn’t acquire braking energy to feed its batteries on this freeway leg.
Tellingly, for the first urban 50km the Prius was in EV Mode for a staggering 61 percent of the time. On the freeway this tumbled to 15 percent.
Meanwhile the C4 Cactus’ 1.6-litre turbo-diesel makes a burly 230Nm of torque at just 1750rpm, needing half the revs to produce more torque and gliding the small hatchback along with insouciance and little fuel usage.
Back at the service station, our real world combined-cycle trip computer claims are in. Over the 103km travelled, the Toyota computer read 4.3 l/100km with a 32km/h average speed. Over the same distance, the Citroen claimed 5.0 l/100km showing an identical average speed.
And, at our time of refill, regular unleaded was 102.5 cents per litre versus diesel’s 102.9c/l. Not much in it there.
But here’s the thing: at the bowser the Prius refused to accept more than 3.35 litres, and the C4 Cactus gulped down 6.0 litres.
Both were brimmed to overflow point, time was allowed for each to settle, and yet nothing more could fit. Each trip computer was out by 1.0 l/100km, the Toyota’s pessimistic, the Citroen’s optimistic.
In other words, measurement of the actual fuel used (over 103km) points to a 3.25 l/100km result for the Prius, versus 5.83 l/100km for the Cactus.
Even allowing for discrepancies with each bowser (one filling from the petrol bowser, the other a diesel), it would be highly unlikely to have such a discrepancy on such a small fill.
Just for fun, we reset the trip computers again and returned to the Sydney CBD outside of peak-hour on both freeway and flowing arterials. Over another 23km the Toyota trip computer read 3.3 l/100km to the Citroen’s 4.3 l/100km. For one of these contenders, it’s game over.
TMR VERDICT | Who wins the ‘economy showdown’?
Let’s place aside fuel consumption for one moment. Conceding the $5000 price difference between the two contenders, which, in city or country, is the better car to drive?
The answer, clearly, is the Prius. While the Toyota has an image problem with some buyers – the new one is no looker – the Citroen evokes charm and character that is both quaint and quirky.
However the Prius feels more mature to drive, is quieter and quicker, with similarly fluent steering and smooth ride quality. And, despite being a medium-sized liftback, it has a larger boot and more rear legroom than the small hatchback-cum-SUV C4 Cactus.
Given today’s fuel prices, on our combined-cycle test results and the 15,000km the average Australian travels each year, the Toyota will drag $515 out of your hip pocket at the bowser annually versus $926 for the Citroen.
Both vehicles have capped-price servicing plans, with the Prius needing six-month or 10,000km checks, at a total cost of $840 over three years or 60,000km.
The C4 Cactus requires annual or 15,000km servicing, but its plan is quite a bit more expensive than the Prius, costing $1475 over three years/45,000km or $2235 if 60,000km comes up first (though it does have a six-year warranty to its rival’s three years).
Hybrid versus diesel, then? We have a clear winner in affordable petrol-electric technology.
And that’s the Toyota Prius, even allowing for the $5000 premium it carries over the Cactus.
Citroen’s Cactus surprised us for its capability and appeal at the wheel, but so too the Prius. What the Japanese brand has done is create a better-driving $35,000 family car that happens to remain the benchmark for frugality.
We can confidently recommend this supercar of economy for reasons other than low fuel usage.
As for the official regulatory ‘controlled’ fuel consumption tests? As ever, it’s best to take them with a grain of salt.
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