We say MPG for PHEV Prius but not the Volt. Isn't it the same thing?

I was just thinking about this. For aftermarket PHEV Priuses, people report MPG numbers of 100+. We don't argue that it's not fair or not accurate. Yet with the 230MPG Volt, we do. Isn't the Volt the same concept as a PHEV Prius except with a much larger battery? This is just something to think about.


Note to WebMaster: We need a separate forum for "Plug-In Hybrids."
(is there already one? did I not see it?)

True, but this is casual conversation and the owner usually tells us how much electricity they've bought as well!

In comparison GM is trying to force EPA into using their protocol for 'measuring' fuel consumption, as the officially advertised figure - remember, car makers can only advertise government-approved figures so that you're actually comparing like-with-like. Which, in the case of the Volt, you're not when comparing it to any regular fossil-fuel-powered vehicle. It's even way above what has been given as MPG equivalent for a pure EV: a 2000 Nissan Altra EV is given as 117 city, 130 highway. The sticker originally said 29 kWh per 100 miles city, 26 highway - these figures have been discounted using the formulas for conversion to the new tests, then converted using energy-equivalent.

The Volt is propelled only by the electric motor. Once the battery is discharged the ICE powers the electric motor. IMO the existing EPA tests probably do not report "fair" or "typical" results. Reporting total range at set speeds regardless of the type of fuel used may be the most useful benchmark.

Would you want an mpg rating on a Tesla in the event someone plugs it into a gasoline powered generator?

I'm feeling pessimistic about PHEVs after reading this thread. They may be doomed by consumer's inability to grasp the kWh.

Ahh, that's only a bit tongue in cheek. But attempting to translate a battery charge into mpg is inane, simply because it depends on the distance driven between charges and the electrical/petrol blending. IMO, the reasonable way to handle this business of the fuel economy sticker is to note the useable battery capacity, range of Kwh/mile on the testing protocols, and mpg when the battery is depleted.

I would agree entirely. stated another way:

How 'bout two sets of numbers for plug in hybrids. One to estblished by a standard test that provides electric ranges for hwy and city driving while in ev only and one set that establishes mpg after electric range is expended.

The ev range could be a simple statement of the standard epa cycles driven to ice/extener startup. After ice/extender startup the standard epa cycles are self explnaditory.

These could be easily extrapolated to your expected driving resquirements.

Maybe you didn't argue about it here. I was labeling it FRAUD in another forum, both on PHEV Priuses and on AFS Trinity, long before joining PC.

As an electrical engineer, I will demand two separate sets of figures, one for electric-only mode, one for gas-only mode. Anything less is garbage.