Ну и в принципе, да, Приус и правда эффективен:

Three things.

1. Loading: the body is relatively small, light and streamlined. Smaller, lighter, and streamlined cars will always get better fuel economy than large, heavy and “boxy” designs.
2. Efficiency: The engine is incredibly efficient, Toyota claims 42% peak thermal efficiency for their newest Atkinson style 4 cylinder engines. Toyota redesigned the electric control system to reduce resistance.
3. The hybrid feature: the planetary gear transmission uses two electric motor-generators and a gasoline engine to keep the engine operating at its peak efficiency, combined with batteries that fill in power when necessary and allow the engine to simply stop when possible. The engine doesn’t run when the car is sitting in traffic, coasting, going downhill, or moving slowly.

1 - говорили, коробка на колесах, легкая, не интересная, и т.д.
2. - да, делают ставку на другой цикл - выжимают из бензина другую эффективность, при том, что у дизеля она просто недостижимая для бензина и так
3. - кстати, самая важная составляющая, манера езды - я сейчас могу при той же скорости один маршрут проехать с расходом 5.8, а могу 6.6 - легко, только из-за манеры ускорений или просто включив эко-про, против спорт+ (трафик не даст разницы в скорости вообще, если по 340 ехать до города и обратно - так в Приусе по умолчанию Эко-Про...

Вот еще подробно про приус - японцы прямо загнались с этим:

Because it was originally designed for extremely low emissions, a side benefit of that is fantastic fuel economy

The engine runs using a different mode called Atkinson Cycle which is far more efficient, produces low emissions and has excellent fuel economy
The downside of Atkinson Cycle is that it does not produce a lot of low end torque
Regular cars run on Otto Cycle, so they produce a lot of low end torque but burn a huge amount of fuel to do that
Once the car is moving, there is no need for all that low end torque so the Otto Cycle engine keep wasting fuel
So what Toyota did was to add an electric motor which has phenomenal amounts low end torque (enough that it can easily drive the car by itself) to move the car and get it going using battery power
Then the gasoline engine kicks inland takes over when its most efficient
There is only one forward gear in a Prius (equivalent to the highest overdrive gear in ordinary cars) so the Prius is more efficient because it doesn't need all the gears in ordinary cars
Prius is also smoother because there is no gear shifting, they are liquid smooth accelerating at speed
Then when the Prius is up to speed, the engine has excess power and so that power is used to charge the traction battery so that energy goes back into the car
Then when driving the computer will shut off the engine and run on battery power as often as is possible
And of course the regenerative bracing means that when the driver steps on the brakes, the computer will connect the motor to the batteries in reverse so it charges the battery which slows the car down which of course means that you get that energy back, below 9 MPH then the disc brakes stop the car
All together this is more efficient and the Prius delivers better fuel economy
Another advantage is that the brakes and engine last much longer because they ar not used as much as on an ordinary car