Although the hot issue is in the current market, specially the continually rising fuel prices at the petrol pump; pure hydrogen is an pricey commodity, hard to keep and is therefore still unlikely to be a severe contender in the future fuel debate for vehicles. Hydrogen cars will most likely not be economically justified in the near future unless it is produced from coal, as this is a much less expensive method enabling the straightforward energy transfer it is necessary to power such car engines and fuel cells as those found in cars.
There's a deal controversy surrounding the subject of hydrogen vehicle like a debate between your claim that only water arrives from the exhaust pipe on cars with internal combustion engines
