Those most critical of the hybrid and electric vehicle segment often highlight the huge expense of battery replacement as a primary reason to avoid the electron-peddling powertrains. Thanks to Toyota's latest round of price drops, however, there's less to crow about on the expense front, with the 10 year/150,000mi (240,000km) replacement period only requiring an outlay of about $2,500.

While typical maintenance costs for a standard vehicle won't rise quite so high, barring some major mechanical malfunction, the drop to $2,299 for 2000-2003 models and $2,588 for 2004-current models marks a significant improvement over the previous $2,985 replacement price. Apparently, the warranted period of 10 years/150,000mi (240,000km) or 8 years/100,000mi (160,000km), depending on state of purchase, is a conservative estimate - very few of the battery packs have actually required replacement, reports Ward's Auto.

John Hanson, a Toyota spokesman, says that about 300 of the units have needed replacement over the car's lifetime thus far, despite there being nearly two-thirds of a million of the cars on the road.

The current battery packs are nickel metal hydride, or NiMH, units, which is relatively low-tech in comparison to the upcoming lithium-ion batteries to be used by the Mercedes-Benz S400, BMW's ActiveHybrid 7-series and Chevrolet's Volt plug-in electric vehicle. Nevertheless, the exceedingly high reliability rate shows the value in using a mature technology, despite the obvious compromise in overall electrical capacity.

Next-generation Prius models will use plug-in technology and feature upgraded batteries, however, as Toyota moves to stay a step ahead of the Volt, at least in terms of timetable, if not performance. A trial run of the plug-in Prius is already underway in the UK.