Toyota to build new Prius in US

Current Prius peak efficiency is 38%, current vw clean diesel 1.9L is 42% and there are much more efficient diesels. Toyota in the lab has NA at 42% and turbo charged at 45%. Just because they are toyota I would expect a non-turbo in the next prius, but going from 38 to 42 will get you to 55mpg. They also can reduce rolling resistance and improve the battery. There is definitely room for incremental improvement, the the big move to using less gas is pluging it in

Aptera is able to drastically reduce rolling resistance, weight, and drag by making it a 3 wheeled vehicle. Since a chinese motorcycle company bought aptera, its likely to get some vehicles into customers hands. Part of the plan is to be low cost, and a serial range extender makes the most sense, powering the motor on the rear wheel.

 

For a laundry list of potential improvements, see the print version of Better Mileage Now--Improving the Combustion Engine, Scientific American, Feb 2010. This list is for improvements compared to an ordinary non-hybrid. While Prius already has about half the listed items, the other half still contains plenty of potential for more improvement.

 

The Gen3's EPA's numbers were ~10% higher than the Gen2's but from where I sit it didn't happen in the real world but it is easier to get the same number.

I believe the Prius will continue to be supersized regardless of the place of assembly.

The 1.5l in the c is not your Gen2's engine.

 

I don't have a SA subscription but thanks for the link.

 

I'm not sure what was in that article but ...

If the prius gets a di engine with 42% efficiency they can drop the size to 1.6L with the same power That should trickle down to increase city milage even more.

Toyota targets 45% thermal efficiency for engines in next-gen hybrids

Concept 1 is probably close to the mazda skyactive design. long stroke really just means undersquare, with the stroke longer than bore. Mazda increased the thermal efficiency further by changing the shape of the piston face, to create even a smaller combustion chamber. This along with di and changed manifolds allowed them to get to 13:1 compression with regular gasoline without knock. Mazda also uses variable lift valves, which allows them to use valves instead of the throttle plate to set the amount of air in the cylinder. Toyota has all of this technology, its just a matter of the added cost. Concept 1 should be able to either downsize the ice with the same power, or reduce rpms depending on the power toyota chooses for the ice.

Concept 2 adds cost and efficiency with a turbo. I doubt we will see it on the gen4 prius, it simply doesn't need more power.

There is also the idea that HCCI may be coming around 2020, which would ignite the gasoline with pressure instead of a spark, this mode should be even more efficient in low load situations like steady state driving. It offers the benefits of diesel with lower pollution and costs, but is still in the lab.

 

YMMV, isn't that always the way. They have some stats with mileage, hypermilers improved, but only a little bit, the biggest improvement seems to be those with trips that had the worst mileage. That goes with your -easier to get the same number. The new engine is more efficient on a larger range of power levels, but it only increased peak efficiency from 37%-38%, that along with higher rolling resistance from higher weight and wider tires makes it only a small gain for those that were doing well before. EPA city was 48 improved to 51, about 6% and here routes and distance have a great deal of influence, highay mileage up 7% and that seems to reflect the real world.

The bsfc map of the engine by itself is much better though. If the car had changed the drive train and cd, but kept the same frontal area and weight (both increased) then improvements would have been more. Likewise if the prius c had the prius liftbacks cd and drivetrain but its smaller frontal area and weight (adding back the difference) it would have improved much more.

Prius C's engine is mostly a carryover from the gen II, which is mainly the 1997 engine with a higher peak rpm and better valving. They did change the motors and batteries and added cooled egr. It did not get the efficiency gains in the gen III engine.