By using an electric car are you helping to save the environment?

Essentially yes. There are exceptions though. In some places where coal is the primary source of electricity, a hybrid vehicle may be better.

The following data is current as of 2018:

The MPG ratings determine what MPG a gas powered car would have to get to be equivalent to an EV. The regions correspond to power grids. In parts of Hawaii, all you need is a car capable of 35mpg which is not to hard to do. In Florida, it would be 58mpg. Offhand, I can’t think of an ICEV that gets that kind of mileage.

And while the numbers are current for 2018, they are changing. The grid continues to get cleaner as old coal plants are closed in favor of green energy like solar or especially wind. This is the same chart from 2015:

As you can see, in 3 years, quite a few states got much cleaner and this trend is expected to continue. So a fuel sipping hybrid that is superior to an EV this year may not be next year.

One other caveat. Currently EVs cost a bit more CO2 to produce because the batteries are somewhat carbon intensive. This is not too hard to “pay back” during normal operation as EVs are usually so much cleaner. In most places, the pay back period is a few months of normal driving. But some people don’t drive much at all. If you only put 1000 miles on per year instead of the normal 12000+ miles, it will take a lot longer to recap the initial carbon debt load. However, this should be a temporary condition. Tesla for example is committed to using renewable energy in their Gigafactories so eventually EVs will be even cleaner to produce than ICEVs.