Toyota Motor Corp. and weather information provider Weathernews Inc. have started tests to improve the accuracy of rain forecasts by using real-time data from networked cars' windshield wipers.

In the tests, which began Friday in Tokyo, Osaka and Aichi Prefecture, Weathernews receives data on wiper movements from Toyota cars via the internet and analyzes it together with data collected from its observation network, which covers 13,000 locations across the country.

The companies assume that wiper operations correspond to the presence or absence of precipitation, and that wiper speed indicates downpour strength.

Weathernews that said its rain cloud radar used to detect and predict rainy areas cannot detect precipitation from clouds at 2,000 meters or below, and that its ground observation tools are limited.

Toyota, Japan's biggest automaker by volume, said it hopes to provide drivers with detailed weather information in real time to enhance safety.

Weather information is one of the in-vehicle services that Toyota has been focusing on.

Starting with the rollout of the Crown and Corolla Sport in June last year, the automaker aims to have nearly all domestically sold cars be equipped with internet access.

Such connected cars will allow drivers to get real-time vehicle data and information about restaurants, hospitals and other places.