H2-powered ICE vs. fuel cells
 

Hey guys,

Following a discussion with @RaceAddict, and being that I had a bit of time on my hands (gotta appreciate those last weeks before your firstborn arrives), I looked into BMW's 750hl program to see what kind of results they got in the real world.

Those were factory hydrogen-powered e38 7-series that used a 5.4L V12 modified to run on either gasoline or hydrogen. It made 326hp on gasoline, but was down to 204hp on H2, which translated to a 0-62 time of 9.6s. BMW made about 15 of these cars and racked up about 100k miles across the entire fleet before tearing them down and moving on to the next-gen e65 7-series for their hydrogen trials (see 745h). Rumor has it they had a few e32 735i's running on H2 before the e38 program, but I haven't found evidence backing that up.

Long story short I wanted to see if they got decent economy compared to a fuel cell. The short answer is: not really.

BMW said they got around 350km / 217 miles of range out of a 140L tank hydrogen tank that ate most of the trunk. This tank is the same size as the Mirai's, which holds 5.6kg of H2, so we'll assume it had the same H2 weight capacity.
That's 1,6kg of H2 for 100km, or 39 miles per kg, or 53c per mile at current vehicle-ready H2 price. About as costly as a car getting 7.5mpg on $4/ga gas.

On the other hand, the Mirai with 17" wheels is rated @0,79 kg per 100km, or roughly 80 miles per kg. It's the same size as an e38 7-series, and gets to 60 about 2" faster.

So it appears that when it comes to H2-powered cars, the ICE gets about half the fuel economy of a similar fuel cell-powered vehicle. And it therefore seems unlikely we'll see H2-powered ICEs on anything else than a niche market.

Anyway, just wanted to post that somewhere in case another person on the interwebs asks (her)himself the same questions.

Holy sh*t!! I didn't know I was getting a firstborn!! I had better have a chat to the wife.