Are hybrids still relevant?

It's like the fabled race between the tortoise and the hare.

The tortoise – internal-combustion engine technology – is making slow but incremental gains in lowering emissions and reducing running costs.

The hare – battery/electric powertrain technology – is rapidly gaining on the tortoise, but when will it overtake?

And where does that leave hybrids – including the plug-in variety?

It was once anticipated that hybrids of all kinds would be the stop-gap to bridge the divide between conventional cars with piston engines and battery/electric vehicles (EVs). Consumers would gradually wean themselves off conventional cars by choosing hybrids, then plug-ins, followed finally by pure battery/electric cars.

But it has been a long, slow slog to convince Australians to buy hybrids. And plug-in hybrids have been even harder to sell, with Holden quickly giving up on its Volt, for example. Rapidly advancing battery technology was bound to benefit plug-in hybrids as well as EVs, but not fast enough, it seems.

BMW has recently dropped the range-extended i3 from sale in Australia. The full-electric version of the i3 already achieves BMW's goals, without any need for the two-cylinder petrol engine on board to keep the battery charged.

Returning to the tortoise and hare metaphor, plug-in hybrids are held back by their reliance on internal-combustion technology to extend range. The galloping pace plug-in hybrids could achieve in earlier years has settled down to the canter of a Shetland pony.

And in development terms, hybrids that don't actually plug into a power outlet to recharge the on-board battery – such as Toyota's Prius or the basic Hyundai IONIQ – appear to be loping along with all the alacrity of a sleepy labrador.

We have previously studied the cost of running an electric vehicle against the cost of running a conventional car. But how do all four powertrain types compare when subjected to the same exercise?

We settled on much the same constants this time around: Five-year ownership and 28 cents per kilowatt/hour for EVs and plug-ins, but $1.50 per litre of petrol or diesel rather than $1.40. Here's what we learned...

Both Hyundai's i30 and IONIQ models are small cars, according to industry sales statistician, VFACTS. For this exercise we felt confident we could draw a valid comparison between petrol, diesel, hybrid, plug-in and full-electric models for cost of ownership. To iron out specification discrepancies as a factor, we settled on the high-spec i30 Premium models to contrast with the IONIQ.

According to the Green Vehicle Guide the plug-in IONIQ only uses 9.4kWh per 100km. The electric IONIQ, without the benefit of a petrol engine to provide some motive power draws 11.5kWh from its battery.

Assuming that owners of the plug-in IONIQ will keep it fully charged at the start of every day and only use up to its all-electric range of 63km per day, the electricity consumption will be higher (but at lower cost) and the petrol consumption will be reduced to practically zero. We went with the official fuel consumption figure for the petrol consumed.

Hyundai i30 Premium (petrol auto)
Purchase price: $32,790
Official combined-cycle fuel consumption: 7.4L/100km
Fuel cost over five years at 20,000km a year: $11,100
Combined cost over five years: $43,890

Hyundai i30 Premium (diesel DCT)
Purchase price: $35,490
Official combined-cycle fuel consumption: 4.7L/100km
Fuel cost over five years at 20,000km a year: $7050
Combined cost over five years: $42,540

Hyundai IONIQ Elite (hybrid)
Purchase price: $33,990
Official combined-cycle fuel consumption: 3.4L/100km
Fuel cost over five years at 20,000km a year: $5100
Combined cost over five years: $39,090

Hyundai IONIQ Elite (plug-in)
Purchase price: $40,990
Official combined-cycle fuel consumption: 1.1L/100km
Fuel cost over five years at 20,000km a year: $1650
Electricity cost over five years: $2520
Combined cost over five years: $45,160

Hyundai IONIQ Elite (electric)
Purchase price: $44,990
Electricity cost over five years: $3220
Combined sum: $48,210

Conclusion: Contrary to the 'sleepy labrador' analogy, the IONIQ Hybrid currently delivers Australian consumers the lowest cost, relative to equipment level, price position and running costs among this selection of Hyundai models.

The only qualification is whether the IONIQ Hybrid can actually achieve anything like its combined-cycle fuel consumption figure in the real world.

But even in the event that an owner could average no better than 5.0L/100km, rather than the official consumption of 3.4L/100km, the IONIQ Hybrid still comes out ahead for value. Over a 10-year timeframe, the IONIQ Hybrid extends its lead over the i30 diesel as the lowest-cost option of the five powertrain variants.