It looks like Audi has completed its assessment and has come to a conclusion that it will have to increase the number of diesels in its line-up in the U.S. Audi’s sales figures prove that diesel cars are preferred to their petrol counterparts. They seem to be a popular fuel economy and performance choice among Audi buyers.

Last year, Audi introduced Turbo Diesel Injection versions of the Audi A3 and Q7 in the U.S. marketplace. The luxury car maker was rather surprised to note the better-than-expected success of the diesel models. Audi has now decided to more than double its existing diesel portfolio in the next year or so. That’s what Scott Keogh, chief marketing officer of Audi U.S.A., had to say in an interview with Green Car Advisor.

Scott Keogh, however, did not disclose which models would be added. But, Audi USA spokesman Brad Stertz noted that, in the past Audi had said it was “looking at the possibility of TDI for the A8, A6 and A4,” all contingent on “working through packaging of the TDI equipment in different models, emissions, and other regulatory testing.”

Mercedes-Benz, BMW and Audi have always been fighting each other in sales to reach the top spot. It is to be noted though, that out of the three German luxury brands, Audi is the most excited about boosting its diesel inventory in the USA. Audi’s diesel cars haven’t let it down. They have posted better sales than diesel cars from both BMW and Mercedes-Benz.

TDI is “definitely a part of the growth and success we’re having in the [U.S.] marketplace,” said Keogh. For the month of July, Audi posted a 22 per cent increase in sales in the U.S., and the Jan-Jun period happens to be the car maker’s best six months ever in the marketplace. It looks like Audi is heading in the right direction for a record annual performance.

As mentioned earlier, it was just last year that the diesel A3 was launched in the U.S. But, this variant now represents nearly 50 per cent of the model’s overall sales. “If you look at last year’s A3 sales number for the gasoline version, it has stayed essentially flat this year,” Keogh said. He said that the numbers were beyond their expectations. The luxury car maker had foreseen just 15-20 per cent of the overall sales of the A3 and Q7 coming from the diesel variants.

As for the A3, the diesel business growth has been 100 per cent incremental. The diesel variant offers growth without the substitution issues of losing sales in one category because of gains in another. As for the Audi Q7, the TDI version represents nearly 40 per cent of overall sales.

Consumers in the U.S. have begun favouring diesel powertrains possibly because of the fuel-economy gains of diesel motors over gasoline engines. Diesel prices are within a dime or two of gasoline per gallon. Diesel variants offer a 20-30 percent fuel economy advantage over gasoline versions. However, it is the younger and richer consumers that buy the diesel Audi cars. Audi charges a price premium of about $1,300 for the four-cylinder A3 TDI over the gasoline-powered four-cylinder A3.