![Chevrolet Bolt EV being charged outside Go Forth electric-car showroom, Portland [photo: Forth]](https://images.hgmsites.net/tmb/chevrolet-bolt-ev-being-charged-outside-go-forth-electric-car-showroom-portland-photo-forth_100606247_t.gif)
In the last few months, it has become clear how much of an effect the federal plug-in vehicle tax credit has on sales of electric cars. The tax credit on Teslas was cut in half in January, from $7,500 to $3,750, and its sales dropped from more than 90,000 cars to 63,000 after the tax credit was cut. Dec. 31, 2018 was the last day the full credit...