SANTA MONICA, Calif. -

Incentive spending hit a five-and-a-half-year low during April, which points to the extreme likelihood that automakers are stockpiling their new vehicles for an impending supply dearth, according to Edmunds.com.

Car companies spent an average of $2,118 per new vehicle sold on incentives during the month, the site estimated. This marks a 19.6-percent year-over-year slide and a 10.6-percent drop from March. The last time incentives were this low was October 2005, when the average spending was $1,962 per vehicle sold.

“This is the clearest indication yet that automakers are gearing up for inventory shortages,” pointed out Edmunds director of industry analysis Jessica Caldwell.

“Demand for new cars has been growing as economic recovery has strengthened, but now the industry may experience a hiccup if consumers decide to wait for the next deal to come around, which may not be until the autumn,” she added.

Interestingly enough, there has apparently already been some waning in consumer interest, according to analysis on Edmunds’ AutoObserver.com from the company’s chief executive officer Jeremy Anywl.

The seasonally adjusted annualized rate surged to 14.7 million units at April’s outset, but slowed to 13 million by the final week of the month.

“April sales usually start slow and then jump after April 15, which may have something to do with tax-filing day,” Anwyl said. “This year we have seen the opposite pattern.”

Moving along to break the incentive data down further, Edmunds found that the Big 3 spent an average of $2,683 per vehicle sold during the month. This compares to March incentive spending of $3,081.

European OEMs spent $1,885 per vehicle sold during April, which is $37 less than the average amount spent in March.

Japanese automakers spent $1,696, compared to $1,932 during the previous month. Incentive spending for Korean brands averaged $1,285 per unit sold, a decline of $38 month-over-month.

Of the top six OEMs, General Motors spent the most on incentives ($3,016 per vehicle sold), but this was still down $243 month-over-month and $285 year-over-year.

Toyota had the lowest incentive spending of the six ($1,687) per vehicle sold. All six decreased their average incentive spending on both a year-over-year and month-over-month basis.

Overall, aggregate incentive spending fell 15.9 percent sequentially to a sum of about $2.5 billion. The Big 3 commanded a 56.9-percent share as their spending totaled $1.4 billion. Japanese OEMs were next with a 30.3-percent share ($751 million), followed by European automakers at 7.5 percent ($186 million).

Korean automakers took a 5.4 percent share, spending a total of $133 million.