As always, the source of the base data is InsideEVs for EV/PHEV sales and the St Louis Fed for car sales. I have seasonally adjusted the underlying data, using my variant of the NBER's X-11 program. InsideEvs is having trouble estimating EV sales because some manufacturers now refuse to split out EV/PHEV sales (presumably because it's too embarrassing), so they haven't yet provided an update for global EV sales (although I now have better data for total global car sales, including data for 2017). So I haven't updated the global charts.
On a seasonally adjusted basis (there's seasonal strength in November/December and weakness in January/February) US EV/PHEV sales are growing strongly, as is their percentage of total car sales. The growth slowdown in 2017 while the market waited for the production ramp up the Tesla Model 3 and the new Nissan Leaf is well and truly over.
Disclaimer. After nearly 40 years managing money for some of the largest life offices and investment managers in the world, I think I have something to offer. These days I'm retired, and I can't by law give you advice. While I do make mistakes, I try hard to do my analysis thoroughly, and to make sure my data are correct (old habits die hard!) Also, don't ask me why I called it "Volewica". It's too late, now.
BTW, clicking on most charts will produce the original-sized, i.e., bigger version.