Auto Manifesto

November 24, 2008

Chevy Volt

An article in Automobile magazine (Dec. 2008) speculates on tax incentives for purchasers that I estimate would put the full retail sticker at around $45,000.

The car itself will feature a 1.4 liter iron-block gasoline engine, producing 53 kW (71 hp), and the batteries will be kept in a 30% to 80% state of charge. The generator will only be used to power the car, not charge the batteries.

Reading between the lines, this is a way to obtain the maximum fuel economy rating and save money.

In theory the mpg rating will be determined by the distance traveled divided by the amount of electricity and gasoline used. But if the EPA is using the term miles per gallon I could see them not counting the electricity used. For example, if the car travels 70 miles on one battery charge and a gallon of gasoline, and the battery range is 40 miles, it is possible the mpg would be calculated as 70 miles / 1 gallon = 70 mpg, which as I’ve stated before would be misleading and inaccurate. I’ve seen articles guessing 100+ mpg.

Anyway, since electricity is less costly than gasoline, it makes more sense not to use electricity generated by gasoline to charge the batteries. Instead the electricity from gasoline is only used to propel the car once it runs out of battery electricity obtained via the power grid.

The motor, generator, and engine form one assembly. This indicates the architecture is intended to be modular and scalable for other vehicle models and platforms. Future developments will likely include running HCCI (Homogeneous Charge Compression Ignition) at a constant RPM. According to Automotive Engineering magazine, that’d be worth about 15% additional efficiency without the added expense and complexity of a diesel engine’s emissions control system.

It’s likely tuners and small volume manufacturers will offer upgrades and performance projects, provided parts and components are available and not too scarce. Can you imagine, say a mid-engine sports car, using a powertrain based on the Volt?

This car is a game changer. There’s plenty of risk as it is, but I’m concerned that it could be game over for General Motors if they don’t survive the current downturn. Hope it makes it to market and GM is around to continue development.

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