Which hybrids had the smallest engine?

What are you getting at? The Prius has a 1.8 which whilst small for the US market, is regarded as quite large over here. But if I recall, it works in a way where it gives optimum efficiency.

Large(r) cars have often had much smaller cars here. The Jetta with a 1.4 is adequate but the much larger Skoda Superb has had a 1.4 litre engine for quite some time. Imagine a car this size with such an engine and has similar performance to the Prius. Dead easy to imagine with petrol costing over $8 a gallon. (the car is also much cheaper to buy than a Prius)

 

Yeah, with our 2nd gen Civic Hybrid, it was kinda cool: 1.3 liter 4 cylinder, with 8 spark plugs.

 

"Dual ignition promotes engine efficiency by initiating twin flame fronts, giving faster and more complete burning and thereby increasing power.[6] Although a dual ignition system is a very effective method of achieving optimum combustion and better fuel consumption, it remains rare in cars and motorcycles because of difficulties in siting the second plug. Alfa Romeo Twin Spark cars (eponymously) use dual ignition, as do Honda cars with the i-DSI series engines.[7] In 1980 Nissan installed twin sparkplugs on the Nissan NAPS-Z engine, with Ford introducing it on the 1989 Ford Ranger and 1991 Ford Mustang four-cylinder models. Several modern Mercedes-Benz engines also feature two spark plugs per cylinder, e.g. the M112 and M113 engines. Some motorcycles, such as the Honda VT500 and the Honda NT400 Bros, also employ dual ignition.[8] The Ducati Multistrada has been modified for 2012 to have "twin-plug cylinder heads for smoother, more efficient combustion", the change contributing to a 5% increase in torque and a 10% improvement in fuel consumption.[9] The 2012 Bajaj Pulsar 200 NS has three spark plugs per cylinder.[10]"
Dual ignition - Wikipedia, the free encyclopedia

I knew about the Ranger's 4 cylinder engines having two spark plugs for more efficient burn, but not that that it could benefit an engine that was a liter smaller like in the Civic.

 

Off topic, but it is fun to look at those engines and speculate about possible conversion to small aircraft engines. I would feel better flying a home built with dual ignition than single ignition.

 

It would probably be easy to come by one of the 2.3L 4cylinders from the Ranger. It was produced for at least 11 years, and with the newest being over tens old; a used one should be reasonably priced. I don't know if the newer 2.5L that came out in 2001 or 02 still used the dual plugs though.

 

Just occurred to me that these dual spark plug automotive engines may not be truly dual ignition. The rest of the ignition system may not be doubled, since such redundancy isn't a safety concern for land bound cars.