ATLANTA –

Manheim chief economist Tom Webb crunched the first-quarter reports of the seven publicly traded dealership groups — CarMax, AutoNation, Penske Automotive Group, Sonic Automotive, Group 1 Automotive, Asbury Automotive Group and Lithia Motors — and determined these companies enjoyed a same-store increase in retail used-unit deliveries for the 23rd consecutive quarter.

Webb also computed that the sales-weighted same-store unit gain for the quarter came in at 6.7 percent.  Adding in store acquisitions, Webb noticed total used retail volume for the seven groups climbed by 12.3 percent year-over-year.

These group’s gross margins, “which have been trending down for some time,” according to Webb, tumbled again in the first quarter. Webb pinpointed the reading at 9.6 percent.

“That represented a normal seasonal uptick from the fourth quarter’s 9.2 percent margin, but was down from the 9.8 percent margin posted in the first quarter of 2014,” Webb said in a blog post associated with his work with Manheim Consulting.

Furthermore, Webb noted that the average used-vehicle selling price for these dealer groups rose 1.2 percent to $20,457 in Q1.

“This reflected a richer mix of units and a higher share of sales accounted for by certified units,” Webb said. “Higher sales prices and steady margins combined with increased operating efficiencies to produce record profits.

“It’s those profit opportunities that kept dealers bidding at auction,” he went on to say.

Webb pointed out that for his analysis, CarMax’s December-February fiscal quarter was shifted forward one month to correspond to the calendar quarter.