The reveal of the new Toyota Prius included the news that the Japanese manufacturer will offer their main hybrid model with two battery choices, without a real-world, practical distinction between the two.
Toyota either installs a lithium-ion or a nickel-metal hydride battery pack into the new Prius, with their specs being basically the same, offering the same performance and with the same benefits on the fuel economy.
The reason behind this choice is because the lithium-ion battery pack, which equips the higher-trimmed models, is 16kg lighter than the nickel-metal hydride, enabling Toyota to add 16kg of extra kit into the more expensive models and still get the same fuel economy with the cheaper ones as Kouji Toyoshima, Toyota’s chief engineer of the Prius confessed to AutoNews.
Toyota wanted all Prius models to offer around the same fuel consumption, despite the small weight differences between models in the range, and that’s what drove them to that decision.
Toyota says that the US-market Prius Two Eco version offers 53mpg in combined city-highway driving, with the other five trim levels EPA-rated at 50mpg. Models in Europe are rated at 94.2mpg UK (3.0lt/100km) combined fuel economy while Japan’s less demanding testing cycle rates the hybrid’s latest generation at 40km/lt (2.5lt/100km-94mpg US-112mpg UK) with the latter’s conversions to be indicative rather than accurate due to the nature of Japan’s procedure.
The two, rear-mounted battery packs have around the same cost for Toyota because the lithium-ion item features just 56 cells, compared with the 168 cells of the nickel-metal hydride one. Voltage is the same, 207.2 volts for the lithium-ion and 201.6 volts for the nickel-metal hydride.
They even have roughly the same size, with the lithium being 30.5 litres in size and the nickel-metal measuring 35.4 litres. As for those who think that the latter is old tech when compared with the lithium-ion, Toyota says that their latest nickel-metal battery is 2.4 per cent lighter, 10 per cent smaller and recharge 28 per cent faster than before.
This whole thing might be driven by Toyota’s decision to offer the same fuel economy across the range of the new Prius, but we can’t help but wonder how much higher mpg a stripped-down Eco version with the Lithium-ion battery could get.