The current FCV configurations call out a BEV with a FC generator used to charge the battery while underway. A true FCV would be directly driven by the FC without the battery buffer or a combination BEV and FC much like a parallel hybrid.

@Lad:
All FC vehicles have a pretty substantial battery, usually at least 1.5kwh.
That is because fuel cells don't much like ramping output up and down swiftly, so it is much easier to provide for acceleration via a battery, not to mention energy storage in regen braking.
An FCEV can't be a parallel hybrid, as they only have and only use one electric motor, which doesn't care whether it is the fuel cell or the battery which provides the electrons.

Of course you can have more than one electric motor, is you want 4wd or in-wheel motors or such, but they still all accept power from the fuel cell and battery impartially.

That is why the engineering for a PHEV FCEV is far simpler than for a Volt or such, and why almost all the parts outside the fuel stack and ancillaries itself are exactly the same as in a BEV.

A fuel cell car is a fully electric one which just uses the far denser energy storage provided by hydrogen.

A FCV is electrochemically still a BEV. The FC stack can be considered a "battery, a flow type of battery, with anode and cathode electrodes. The advantage is in the use of H2 at high efficiency and without emission. H2 is renewable synthetic fuel that can be synthesized with the least cost and the highest efficiency, due to its atomical and molecular simplicity. The reason that a synthetic chemical fuel is needed to store RE is that Lithium batteries are too expensive as means of seasonal energy storage in a massive scale.

A liquid-fuel PHEV is more advantageous than a FCV in the near term because one can refuel everywhere, and that liquid fuel (gasoline) is very energy dense, thus permitting a very small fuel tank, of perhaps 4-6 gallons for 300 miles. In the future when H2 stations will be everywhere, then FCV will be just as practical as PHEV, except for the fact that FCV may still require a bulky and heavy fuel tank, thus limiting internal space. If batteries (lithium...etc) can be made much more compact than they are now, then PHEV fueled by gasoline will still have an advantage over FCV due to higher internal space and lower weight.

Also, many people will still be afraid of Hydrogen and won't buy a FCV no matter how much reassurance of the superior safety of FCV vs. ICEV.

You can run the diesel cycle on hydrogen. Mazda rotaries run fine on hydrogen too.

Fuel cells aren't really necessary.

http://www.wpi.edu/Images/CMS/UGP/Hydrogen_Powered_Vehicle.pdf

My point is that a smaller battery + a small ICE range extender is a better bet than a large battery [IMO].

The leaf battery weighs 300 Kg,and is good for 120 miles (or so).
Now, replace this with a 200 Kg battery, and a 100 Kg range extender. Now, you can drive for say 280 miles, and refuel in 5 minutes (if you want to), anywhere.
But most of the time, you will be driving electric, probably 90% of the time. So the amount of gasoline you use per year will be very small indeed, but you have no range problems.

H2 might be cleaner than gasoline, but if you use very little gasoline, you can sleep safely.

"If an ICE is run at its most efficient point and used as a generator yes it can be more efficient than automotive fuel cells."

Please put some numbers and links to that claim.

It seems obvious that this would be the way to go. FCVs often have 100 kW fuel cells, if they can do the job with a smaller fuel cell and more batteries, this is the best configuration.

Now if they can find a way to not have high pressure hydrogen tanks, that would be better. An adsorbant or reforming methanol would be ways to do that. Mercedes had the NECAR designs that reformed methanol and worked well.