Tesla's customer referral programs have proven a little bit controversial, but they seem to be producing good results for the Silicon Valley carmaker.

Last July, the company began encouraging customers to refer friends to buy Model S electric cars, with the incentive of a $1,000 credit for each referral, and the chance to win one of the first Model X crossovers.

A second referral program ended New Year's Eve. This time there were no cash credits to referrers, but there were prizes--including a new Model S P90D with Ludicrous mode and a ticket to the opening of Tesla's battery "Gigafactory."

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Referred customers in both programs got $1,000 discounts, and Tesla got quite a few more sales, according to Ecomento.

Sylvain Juteau--the North American referral leader--estimates that all referrers generated about 5,000 Model S sales.

The Canadian--publisher of Roulezelectrique.com and EVandmore.com--accumulated 34 referrals in the second program, winning a Model S P90D.

Tesla Model S at Supercharger site in Ventura, CA, with just one slot open [photo: David Noland]

Tesla Model S at Supercharger site in Ventura, CA, with just one slot open [photo: David Noland]

Juteau was also the North American winner for the first referral contest. He used the money he won to buy several CHAdeMO adapters, which he gave away to customers he referred in the second contest.

The overall winner was a Chinese Tesla owner named Wei--with 188 referrals in two months.

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For his trouble, Wei got a Model S P90D and an invitation of the opening of Tesla's Gigafactory, which is currently taking shape just outside Reno, Nevada.

The European leader was Bjorn Nyland, at 51 referrals.

Nyland is quite the Tesla enthusiast. Back in August, he claimed to set a Model S distance record after covering just over 450 miles in a loop beginning and ending at the Supercharger DC fast-charging site in Rødekro, Denmark.

Tesla Model S P85D, 2015 Detroit Auto Show

Tesla Model S P85D, 2015 Detroit Auto Show

And in the first referral program, Nyland earned a Model X crossover. His total for the second program garnered a Model S P90D to go with it.

But while Tesla has managed to cultivate the enthusiasm of its customers into more sales, the referral programs have also created controversy.

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During the first referral program, Virginia regulators decided that Tesla had run afoul of a state law prohibiting compensation to people not licensed as car dealers--a practice known in the industry as "bird dogging."

Tesla subsequently cut referring customers in Virginia out of the program--giving $2,000 in incentives to purchasing customers only.

[hat tip: Brian Henderson]

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