Audi sold 2,159 units of its redesigned sub-$30,000 A3 sedan in its first full month in showrooms, contributing to the brand's 19 percent increase from a year earlier to 15,653 vehicles.
Mercedes-Benz's CLA, the sub-$30,000 coupe that helped the brand take the U.S. luxury-sales crown from BMW in 2013, contributed 1,575 deliveries to Mercedes' record April sales of 25,887 vehicles.
The brand's total sales rose 10 percent from a year earlier, led by the CLA as well as gains of 73 percent to 1,909 for its top-of-the-line S-class sedan and 37 percent to 6,056 for the E class.
BMW said it had April sales of 25,202 vehicles, up 9 percent, led by its mid-sized sedans and SUVs.
Mercedes has sold 98,501 vehicles for the first four months, extending its lead over BMW, which delivered 97,579, to 922 cars and SUVs from 237 at the end of March. Sales for Audi through April totaled 50,881.
The figures don't include Daimler's cargo vans and Smart cars and BMW's Mini brand.