South Carolina drivers last year snapped up another 27 hybrids for every 100 already on the road, according a national group using auto researcher figures.

The state posted the sixth largest rate of increase in hybrids between 2012 and 2013 at 27.67 percent, the Diesel Technology Forum said earlier this month.

In 2010-12, South Carolina placed first in the U.S. with a 50 percent increase in hybrid numbers, the forum found.

"Consumers have an ever-growing number of choices for more fuel-efficient vehicles," said Allen Schaeffer, executive director of the Diesel Technology Forum.

The findings are included in a wide-ranging report on vehicles that use diesel fuel usage and those that run off gas-electric or just EV power. The Washington, D.C., based forum said it based the analysis on auto registration figures compiled by R.L. Polk and Co. for the 50 states and the District of Columbia.

While presenting scores of figures, the forum in its public remarks didn't provide specific reasons for individual states' sizable gains - or lack thereof - in diesel and hybrid car registrations and in the rates of growth.

Georgia led all states last year in its heightened hybrid interest, showing a 54.32 percent volume increase from 2012. Oklahoma placed second, up 47.38 percent and auto manufacturing hub Michigan ranked third with a 35.7 percent year-over-year jump. South Carolina beat out California and Missouri in its hybrid percentage increase.

Calculated by numbers, California was far and away the hybrid passenger car leader at 698,560 or close to 25 percent nationwide. Texas came in second at 153,557 and Florida, third at 150,885. Georgia rounded out the top 10 with 76,168 hybrid vehicles.

California was the only state that made the top 10 of diesel passenger cars and trucks while tallying more hybrids on the roads than diesels.

In the U.S. last year, hybrid registration increased by 531,385 while diesel tags rose by 410,040. The forum said its analysis also showed that hybrid sales increased by 64.5 percent from 2010-13 while diesel sales rose by 30 percent. The overall market, by comparison, inched up just 3.6 percent.

"We fully expected that hybrids would outpace diesel sales based on the number of choices available to consumers during this timeframe," Schaeffer said.

"In 2013, there were 23 diesel cars and SUV choices for consumers, but more than double that - 50 choices - for hybrids."

But the forum believes that diesel car and SUV business isn't far away from a growth spurt as manufacturers roll out a larger share of diesel passenger vehicles. "We are poised . to see the number of clean diesel choices grow in the next 18 months to encompass more vehicle classes and price ranges," Schaeffer said.

"Consumers have an ever-growing number of choices for more fuel-efficient vehicles, and this analysis shows that clean diesels are gaining in popularity all across the nation," he said. The forum contends that diesel vehicles are 30 percent more fuel efficient than gas-powered cars.

Among other findings:

- North Dakota was the fastest-growing state for diesels, up 24.12 percent. Following North Dakota were District of Columbia with a 15.94 percent climb and Illinois, up 13.62 percent. Illinois, meanwhile, ranked first in diesel car registrations, up 25 percent. Arizona finished second with a 15.5 percent gain and California third, up 11.3 percent. "We see new registrations of diesel cars, trucks and SUVs growing in all regions of the U.S. - red states, blue states, urban and rural regions alike," Schaeffer said.

- North Carolina ranked seventh in total diesels at 197,305, while Georgia placed ninth at 189,018.

- Texas led in number of diesel pickup trucks at 747,760. North Carolina ranked eighth at 159,679 and Georgia was ninth at 157,332.

- California finished first in diesel cars and SUVs at 93,654, while North Carolina placed eighth at 29,229.

The forum said diesels account for more than 7 million cars and trucks in the U.S., while hybrids make up 2.8 million - based on passenger vehicle registrations in the R.L. Polk data.

Diesel registrations make up 2.8 percent of all passenger vehicles, which include cars, SUVs, pickup trucks and vans. Diesels, though, account for a full 10.6 percent of pickup truck registrations.

The forum broke out top 10 lists by states but didn't publicize figures for all 50 states in any of the categories. As a result, South Carolina's diesel registration total and growth rate weren't immediately available.

"Diesel cars and SUVs are emerging in the U.S. market," Schaeffer said. "While diesels account for about 50 percent of all auto sales in Europe, diesels are a more modest 3 percent in the U.S.," he said.

"But clean diesel vehicles are poised to take off, as evidenced by the number of clean diesels being introduced in the U.S. market," said Schaeffer, who noted that an estimated 60 diesel vehicles will be available by 2017.

"As a result we could see the diesel market in the U.S. reach 10 percent by 2020," he said.

The Diesel Technology Forum categorizes itself as a nonprofit national group geared to "raising awareness about the importance of diesel engines, fuel and technology" while working with policymakers and stakeholders on solutions.

For more information, visit www.dieselforum.org.

Reach Jim Parker at 937-5542 or jparker@postandcourier.com.

Fastest-Growing Hybrid States(All hybrid passenger vehicles, 2012-13)

1 - Georgia, up 54.32 percent.

2 - Oklahoma, up 47.38 percent.

3 - Michigan, up 35.7 percent.

4 - Illinois, up 33.82 percent.

5 - Alabama, up 30.14 percent.

6 - South Carolina, up 27.67 percent.

7 - California, up 27.4 percent.

8 - Missouri, up 27.26 percent.

9 - Hawaii, up 26.77 percent.

10 - Arizona, up 26.32 percent.

Sources: Diesel Technology Forum, R.L. Polk