As American industry has become increasingly global over the last 10 to 15 years, more and more ‘American’ cars are being made with fewer ‘American’ parts and more foreign auto parts. As more electrical components are being used for hybrid and electric vehicles, it is challenging to know where the different parts making up your car are coming from.

For example, while batteries are being made in Japan, the electric motors running off the batteries are made in Korea. It is very difficult to know with any degree of certainty just how ‘American’ your American hybrid vehicle is.

Frank DuBois, a professor at American University’s Kogod School of Business has developed a way to break down what elements of many of today’s vehicles come from where. His work is published annually in a document called the Made In America Auto Index.

Each vehicle receives a score based on several different criteria including engine and transmission production (21%); body, interior, chassis and electrical (50%); research and development (6%); profit margin based upon the site of corporate headquarters (6%); labor (6%); and site of inventory and capital expenses (11%). Scores are then added ranking all of the automobiles on the market based upon their content sources from the United States.

The five most American-made electric vehicles for 2016 include:

Cadillac ELR

The Cadillac ELR is a vehicle that I am sure few of us have ever heard of. It has the drivetrain of a Chevy Volt for the price of a Tesla. As a result, it was largely doomed from the get go.

Because of low demand from American consumers, production officially stopped in February of 2016. However, it was still included in the research by DuBois.

The final score of American sourced content for the Cadillac ELR was 54 with close to half of the overall vehicle being foreign-sourced. This includes components in the body, interior, and chassis of the vehicle. The powertrain also came from overseas.

Ford C-MAX and Fusion Energi

The Ford C-MAX and Fusion Energi are the automaker’s top selling plug-in vehicle. It can travel 20 miles without gasoline.

Manufactured alongside the Focus Electric, the C-MAX has an overall score of 59. This is good enough for a fourth place ranking for electric vehicles in 2016.   Over half of the electrical and interior components were sourced overseas, in addition to the motor.

Chevrolet Volt

The Volt was recently redesigned and lost a few points over last year’s survey. Capable of 61 miles in EV mode, the Volt remained on the list with a score of 61. Half of body, chassis, and electrical components come from overseas in addition to the electric motor.   The redesigned Volt is challenging Tesla for the most plug-in sales this year in the United States.

Chevy Spark EV

Last year, General Motors brought production of battery components for the Chevy Spark EV in-house. This decision gave the vehicle a Made In America score of 63. Most of the car’s body and interior are made in the United States as is the electric motor and transmission.

Interestingly enough, the Chevy Spark EV is assembled in South Korea. As a result, it lost points for labor and inventory but still finished ahead of all of the other plug-ins.

Tesla Model S

The Tesla Model S has the most American content of all electric vehicles for the second year in a row. With a score of 75, it was good enough for a 12th place finish on the index tying with the Jeep Grand Cherokee SRT and ahead of American icons, the Dodge Ram at 74.50 and Chevy Silverado with 72.50.

Half of the Model S’s electrical and body components are sourced overseas. Everything else is sourced in the United States. However, scores should improve once Tesla’s Gigafactory is brought online.