BMW will reveal a redesigned 5-Series in October, and included in the range will be a new electric variant dubbed the i5.

We've already spotted prototypes for the i5, in both sedan and Touring wagon body styles, and BMW on Wednesday provided an update on the progress of the development.

The prototypes have undergone extensive testing in extreme weather to gauge the performance of the battery and other electronics. Extreme cold is a condition that normally takes a toll on the battery's range and performance, and as a result most of the weather tests have taken place in temperatures well below zero.

Such tests also enable the engineers to evaluate how the vehicle performs on surfaces offering little grip. A popular spot for testing is Arjeplog, Sweden. Located close to the Arctic Circle, the area comprises a number of frozen lakes during the winter months where prototypes are regularly tested. Here, engineers have precisely reproducible conditions for testing various vehicle setups, BMW said.

In the i5, the wheel slip limitation function and the powertrain are interlinked. This approach helps improve the speed and precision in which the i5's traction can be adjusted. The result, according to BMW, is a combination of optimum traction when accelerating and high stability when cornering or braking.

Underpinning the redesigned 5-Series, including this i5, is an updated version of the current 5-Series' CLAR platform which is flexible enough to support multiple powertrain types. BMW hasn't provided any specifications, but the same platform features in the i7, the electric version of the latest 7-Series. The i7 features a 101.7-kwh battery, and its range is rated by the EPA at up to 318 miles. A planned i7 M70 grade is also confirmed by BMW to deliver more than 600 hp.

The new 5-Series and i5 should arrive as 2024 models. The i5 Touring probably won't reach the U.S., given BMW's current reluctance to sell any wagons here. An M5 with plug-in hybrid technology is also being developed, likely for an arrival as a 2025 model.

Production of the complete 5-Series range will be handled at BMW Group's plant in Dingolfing, Germany. The plant, which turned 50 this year, is also where BMW builds the 7-Series, 8-Series, and iX.