The idea isn't unique to Toyota - Daimler is expected to offer a hybrid variant of the Smart ForTwo in the near future, with an all-electric version also set to begin testing next year. Combining the efficiency of a hybrid drivetrain with the diminutive size and low-speed use characteristics of a city car is the ideal use of the technology in many ways. Honda has highlighted this fact by exclusively targeting its hybrid systems at smaller vehicles, noting that efficiency gains for larger vehicles, even under similar urban conditions, are not as good.
Toyota's iQ, the standard version of which is powered by a 1.0L petrol engine, is already a very efficient vehicle. Substituting a 0.5L engine for the 1.0L unit while adding a battery supply and electric drive could push efficiency up even further, according to Auto Express. Especially useful would be the expected 15mi (24km) electric-only range, which could cover many of the smaller trips made in urban environments as if the car were a pure electric vehicle (EV) with zero emissions and excellent energy efficiency.
Hybrid models aren't expected to be available for retail sale until 2010. Spy photographers recently caught the upcoming conventional-engine iQ in testing. That car is expected to be available for sale early next year.