The fourth-generation PriusToyota PriusJapan, 1997 > present4 series
62 versions
149 photos
2 videos
is set to go on sale next summer or fall, and ToyotaToyotaJapan, 1937 > present155 models
4570 photos
10 videos
has been caught testing the car. News last year indicated that Toyota was deciding whether to simply evolve the look of the Prius for the new generation or to have a significant change like between the firstToyota Prius Gen.1Japan, 1997 > 20033 versions
8 photos
and second generationsToyota Prius Gen.2Japan, 2004 > 20092 versions
8 photos
. Unfortunately, we still do not know what Toyota has decided.

What will not be the same is the car's technology. Toyota is expected to introduce a major upgrade in tech for the new generation. A move to a lithium-ion battery for the standard Prius is almost certain. The current Prius uses a nickel-metal hydride battery, and the Prius plug-in uses a higher capacity lithium-ion battery. The lithium-ion batteries have a higher density and lower weight than nickel-metal hydride.

The next-gen is also expected to use a larger amount of aluminum, which in addition to the battery, will cut weight by 150lb or more over the current car. The changes, especially a more power dense battery, could increase fuel economy by up to 20%.

After the fourth generation's introduction, Toyota will slowly roll out updated versions of the Prius VToyota Prius vJapan, 2011 > present3 photos
and Prius Plug-inToyota Prius Plug-in HybridJapan, 2011 > present2 photos
.

Source: Motor Authority