(Distance is: 4x ECE-15 cycles of 1 km each, and 1x EUDC cycle of 7 km, so 11 km total. Time is analogous.)
The press release also says the battery range is "up to 25 km".
In short, they are averaging together ε time of gasoline driving, with (1 - ε) time of battery driving, with ε tweaked to get a very high but barely-plausible mpg figure that is in fact complete nonsense. (I hope \epsilon encoded correctly). A big fat lie.
Note there isn't really a discrepancy: the NEDC cycle has a 75 mph component and quite a few accelerations, while the Porsche battery range is given as "up to 25 km", implying ideal, minimal-acceleration driving. So it's reasonable the battery lasts less than 11 km under NEDC conditions, allowing for an ε sliver of gas driving (to keep things finite).
Google's Mark Chu-Carroll devastated Chevrolet when they pulled the same trick with the Volt mileage ("230 mpg!"), on Good Math, Bad Math:
I think thats a bit strong. In reality reading the article convinces me more that the Volt is an extremely good idea since it is based on more realistic maths.
But I agree with everything else, if you buy a car with anything like this kind of preformance and actually expect that mileage then your only fooling yourself.
Lets face it, this is so that the actors and footballers can claim to drive a hybrid while having a car that actually reflects their lifestyle.
The press release mentions that 94 MPG is achieved under the New European Driving Cycle:
http://www21.porsche.com/usa/aboutporsche/pressreleases/pag/...
With a bit of Googling, this means
* 20 minutes of driving
* 11 km (7 miles) distance
http://en.wikipedia.org/wiki/New_European_Driving_Cycle
http://www.dieselnet.com/standards/cycles/ece_eudc.html
(Distance is: 4x ECE-15 cycles of 1 km each, and 1x EUDC cycle of 7 km, so 11 km total. Time is analogous.)
The press release also says the battery range is "up to 25 km".
In short, they are averaging together ε time of gasoline driving, with (1 - ε) time of battery driving, with ε tweaked to get a very high but barely-plausible mpg figure that is in fact complete nonsense. (I hope \epsilon encoded correctly). A big fat lie.
Note there isn't really a discrepancy: the NEDC cycle has a 75 mph component and quite a few accelerations, while the Porsche battery range is given as "up to 25 km", implying ideal, minimal-acceleration driving. So it's reasonable the battery lasts less than 11 km under NEDC conditions, allowing for an ε sliver of gas driving (to keep things finite).
Google's Mark Chu-Carroll devastated Chevrolet when they pulled the same trick with the Volt mileage ("230 mpg!"), on Good Math, Bad Math:
http://scienceblogs.com/goodmath/2009/08/the_chevy_volt_gets...
Lots of other hybrids are pulling the same trick. Here's the numbers behind the Hummer H3 electric (yeah, seriously...):
http://www.rasertech.com/wp-content/uploads/hummer_fuel_econ...
See how it works? The press release summarized this as "100+ mpg":
http://www.rasertech.com/media/videos/the-electric-h3