A challenge to go green

"Honey, I will be home late tonight. I have to charge my Prius."

So there I was, at a Shell station in Bukit Timah Road, damp from perspiration and the drizzle and at risk of being bitten by the Aedes mosquito. I was charging the Toyota Prius PHV (plug-in hybrid vehicle) that The Straits Times is doing a long-term test of.

I reviewed the car a fortnight ago after driving it as if it were a regular non-plug-in vehicle for two weeks. This week, I write about my experience after I plugged the car in.

The Prius does not let you leave the ignition on while it charges. I could have gone into the shop for a coffee, but instead, I sat in the car with the windows down, sending e-mails on my laptop.

An hour and 14 minutes later, the Greenlots (a provider of electric vehicle charging points) app on my phone revealed that 4.17kWh had been delivered for $2.29. The car indicated that I have bought 46.9km of pure electric driving range.

Was it worth my time and effort?

Charging the car was certainly more inconvenient than I thought and I conclude that it takes significant willpower to commit to electric motoring.

A pure-petrol Toyota Vios, after all, can be filled up in a matter of minutes and it does not require me to plan my schedule in advance.

Alas, such is the inconvenience faced by an electric vehicle owner in Singapore who does not live in a landed property. If you live in one, the authorised dealer of an EV model can supply a wall-mounted unit for home charging.

Singapore's public charging infrastructure is growing rapidly, with 28,000 points planned by 2030, according to this year's Budget announcement.

Companies such as Greenlots, SP Group and BlueSG provide the bulk of charging points - both fast and not so fast. Greenlots has a network of 48 chargers at 35 public locations, on top of 106 chargers in 45 condominiums, while the SP Group aims to have 1,000 points by this year.

These points are scattered all around the island in petrol stations as well as malls and other carparks. They are easy to find and use. Their apps indicate the availability of chargers, allow for in-app payment and track charging progress.

An hour is still a lot of time, though. At the end of my 3.2km drive home from the petrol station, the car tells me I have lost 6.3km of range. Harumph!

It did not take many more journeys before the Prius PHV's petrol engine has to contribute again.

On longer expressway cruises, the charge mode can be activated, where the engine acts as a generator to top up the battery. I used this function often, but it also made overtaking a noisy and laborious affair.

In return, I get smooth, silent and theoretically more efficient all-electric city driving. A pure electric car would be more adept at this, though.

Over the next two weeks, I plugged the car in twice.

The first time was at my grandmother's semi-detached house, where I stayed for about two hours and earned an indicated 52km of range.

Then, on a grocery run to City Square Mall , whose location I had deliberately picked for its charging point, the charge was 2.85kWh for $2.43 in 48 minutes. I got 30.4km of range.

Compared with the charge at the Shell station, the electricity costs were higher this time because I was charged by the minute instead of by kWh. At seven cents a kilometre, it costs almost as much as petrol for a regular hybrid Prius.

My four-week test drive, which included a mix of electric-and petrol-powered driving, clocked a total of 454km.

At the end, I find that the petrol tank is emptier by 14.69 litres, costing me $27.10 in 95-octane fuel. This translates to a petrol consumption of 3.24 litres/100km, versus 5.8 litres/100km a fortnight ago when I did not plug the car in at all.

In all, I spent $31.82, or seven cents a kilometre. Not bad.

But I am still not sure if driving a PHV, or any electric vehicle, is worth the time and effort.