Toyota Prius: Behind the Wheel Blog

Read our Toyota Prius news report here.

Filled the tank on the weekend. Contrary to the trip computer readout of 5.1L/100km, average consumption for the tank (including the open-road run from Albury) was actually 5.5L/100km, based on manual calculations. That's taking a fill of 37.04 litres divided by 668.4km over 100. Now much as we'd like to excoriate the on-board 'FRED' for not being able to count, perhaps Prudence wasn't topped up as carefully in Albury as she was in Melbourne. If the fill in Albury was two litres shy of what was possible and there's an extra litre in the filler neck in Melbourne, that would account for the difference.

As Prudence drove out of the service station and up a hill, the trip computer average dropped from over 12.0L/100km to about 8.0L/100km in the space of a kilometre. Just driving around the block (with a downhill section on the return home), reduced the average consumption to 3.5L/100km. It more or less indicates that during daylight hours and confined to suburbia, Toyota's figures for the Prius are achievable.

Since then, Prudence has transported the family along the Eastern Freeway and Alexandra Parade to see the Star Wars exhibit at Scienceworks in Melbourne's west. We parked the Prius opposite a vintage car exhibition that was there on the day. Couldn't help thinking that alone, the unburnt hydrocarbons in the exhaust of the 1940 Ford V8 could just about power the Prius. That's a joke by the way. Please don't write in explaining mathematically how that is/isn't possible.

On the run along Alexandra Parade, the traffic moved very slowly (footy on at the 'G'?). It was our first opportunity to use the EV mode over a significant distance. It worked really well. In this environment (traffic moving up to but no more than 40km/h), Prudence shone. Fuel consumption hovered around trip computer figures of 3.9 or 4.0L/100km. The only problem with EV mode is that once speed exceeds an indicated 48km/h in the Prius, it reverts to default mode, with the petrol engine providing additional torque. So its uses are fairly limited in the Australian urban environment, unless you spend way too much of your time in peak-hour traffic.

Here's a scenario for you -- one that's quite common driving Prudence around Melbourne. There's a stretch of dual-lane carriageway with traffic lights 750m apart. You select EV mode, because the traffic's fairly heavy. By the time you've covered 550 to 600m, the Prius has reached a speed of 50km/h and disables EV mode in favour of the default 'Normal' mode. You brake for the red light at the next intersection and re-select EV mode, because the traffic remains dense.

This is a common occurrence and it's not like you can muck around at 45km/h to stay in EV mode when there are vehicles behind you. So it would be good if, once the driver had selected EV mode, the Prius returned to EV mode after the speed had reduced below the driving mode's ceiling speed. Instead, it stays in default mode, so the driver must manually select EV mode at each intersection. And do you know how many light-controlled intersections there are in Melbourne?

EV mode is otherwise excellent. It needs to be used more frequently than is entirely possible with the way Toyota has configured the Prius, but what's so special about it is this: You can use 75 per cent of the throttle or better, without the petrol engine kicking in. Should you need emergency acceleration and press the accelerator all the way to the floor, the petrol engine will start, to provide added power.

In normal mode, you can't keep up with traffic without the four-cylinder firing up, but in EV mode, you can keep up for brief spurts and not use a drop of petrol. Its range is limited, but it gives you that initial burst of acceleration which makes the Prius viable in slow traffic and the petrol engine can operate more efficiently then as a range-extender, rather than providing supplemetal motive power.

Coming back from a Mercedes-Benz launch yesterday (the new E-Class being the other mass-production car boasting a drag coefficient below 0.26Cd), the Prius also served well on the Northern Ring Road. Even as night fell, the traffic was still heavy and it was possible to use EV mode extensively. With the headlights on and some occasional open-road speeds, it wasn't possible to maintain the low fuel consumption figure from the day before, but it was still around 4.2L/100km by the time Prudence arrived home. 

'Owning' a Prius changes your whole outlook on driving. You become satisfied and sustained with not getting to the front of a line of traffic if you can keep fuel use relatively low. And keeping batteries charged becomes another challenge that takes on larger proportions than just getting three cars ahead through lane-changing.

It's a challenge that puts us in mind of Apollo 13, but without the same dire consequences in the event of failure. Has that parallel occurred to celebrity Prius owner and star of the film 'Apollo 13', Tom Hanks?

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