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Why it's difficult to accurately test the efficiency of a plug-in car

When it comes to electric vehicles and plug-ins in general, the Environmental Protection Agency-certified range is a hugely important number. While actual range anxiety is largely psychological, the magic number does provide a point of comparison of buyers considering one EV over another. The driving distance is also often touted by automakers when marketing their models. Unfortunately, as Green Car Reports finds in a recent deep dive, the way the EPA calculates the figure is a convoluted mess, and discovering the reasons why is definitely worth the read. The issue isn't about bad science but instead comes down to vague wording. The EPA's accepted range test is sourced from an evaluation called J-1634 from the Society of Automotive Engineers, and it seems to provide balanced results for vehicles that automatically reach a single state of charge when plugged in. However for models with multiple charge settings, the situation gets complicated very quickly. Of course, these modes are often created in the software, meaning that a car's certified driving distance can change with just a few taps of the keyboard without the real world results owners might experience actually changing. By showing the test's effects on the certified range for the Tesla Model S, Nissan Leaf and Mercedes-Benz B-Class Electric Drive over the last few years, Green Car Reports makes a compelling argument that it's the evaluation that needs to change. Thankfully, it appears that the solution is a very simple one. Get the details here.

Tesla in talks with BMW about batteries, charging collaborations

With Toyota and Daimler no longer holding Tesla shares, the electric vehicle company might be looking for a new partner – possibly a Bavarian one. In a new interview with Germany's Der Spiegel, CEO Elon Musk confirmed that he has had talks with BMW execs about future collaboration. "We are talking about whether we can collaborate in battery technology or charging stations," Musk said in the interview, according to Reuters. However, a Tesla spokesperson has tempered things by saying no formal agreements are in place at the moment. In the same interview, Musk reportedly praised BMW's use of carbon-fiber-reinforced plastic in its i sub-brand offerings, and said he would like to have a battery factory in Germany in the next five or six years. The possibility of technological cooperation between Tesla and BMW has been a hot topic this year. In June, Musk reportedly met with BMW execs, and the two companies were also rumored to have met with Nissan to discuss charging technology. When Daimler sold off its shares, there was talk of it opening the way for possible collaboration between the two automakers, as well.

Figuring out exactly how much it costs to charge Tesla Model S

Is the Tesla Model S an electricity guzzler? One driver trying to answer that question says it does gobble down more juice than previously thought, but it's not time to make Hummer jokes just yet. First, the goal: Tesla's claims that properly set up home-charging stations can get about a 91-percent efficiency rate. Rob M. from Teslarati has been diligently tracking electricity used by his home charging station – made up of a NEMA 14-50 outlet that was professionally installed and Tesla's Universal Mobile Connector (UMC) – since June, as we reported here. The results for the month that ended July 21 revealed that the Model S was taking in about 82 percent of the electricity it was pulling from the system, indicating an 18-percent loss of electricity. Most EVs are thought to charge at an 88 to 90-percent efficiency rate. The downside to his results? About $26 more per month in electricity costs than previously estimated on about 2,400 miles worth of driving. There is a positive upshot, though: his monthly fuel savings totaled about $334 compared to driving an internal combustion engine vehicle. These early results are intriguing, and make us wonder... Is anyone else checking in on their Model S charging efficiency?