U.S. light-vehicle sales cruised to their 20th straight year-over-year gain in April, with no letdown in sight.

Sales totaled 1.181 million units in the month, good for a daily selling rate of 49,211 over April’s 24 selling days, and 15.1% more than year-ago’s 42,749.

The raw volume even outdid year-ago’s 1.154 million, despite April 2011 having three more selling days.

The month’s SAAR of 14.4 million units surpassed last month’s 14.3 million and year-ago’s 13.1 million. The year-to-date total remained at 14.5 million, well above like-2011’s 13.0 million.

Year-over-year increases likely will continue to improve, especially with hefty double-digit gains expected during the next several months, when comparisons with like-2011’s tsunami-ravaged market will be favorable.

Although some Japan-based vehicle lines started to thin out in April 2011, U.S. dealers didn’t fully feel the impact of the inventory shortage caused by the natural disaster in Japan until May. That’s when sales tanked to an 11.7 million SAAR after having run at a 13 million-plus rate for three straight months.

June’s SAAR fell further to 11.5 million, and the industry did not return to the 13 million-unit mark until September.

The tsunami effect, which was exacerbated later in the year by flooding in Thailand, never totally abated in 2011, meaning monthly sales – barring another natural, or economic, catastrophe – should easily record year-over-year increases for the remainder of 2012.

Chrysler led all major volume manufacturers with a 35.5% increase in April. Its year-to-date sales were up 33.2% and its market share rose to 11.9% in April, compared with prior year’s 10.1%.

Toyota deliveries climbed 25.5% from like-2011, as Prius demand more than doubled. The auto maker squeezed by Ford to claim the No.2 sales spot for the month behind General Motors, with its 15.1% market share barely clipping Ford’s 15.0%.

Despite yielding ground, Ford still posted a 7.1% sales increase in the month.

GM’s deliveries rose 3.2% from year-ago, and its market share improved to 18.1% from a record low 16.5% in March.

Nissan’s April sales dropped a whopping 39.0% from March, but it was able to record a 12.2% gain over year-ago, when it was hit hard by the supply shortage.

Estimated inventory at the end of April totaled 2.816 million vehicles, up 22.1% from year-ago. Days’ supply is estimated at 56, compared with 54 in like-2011.

hstoddard@wardsauto.com