The A-series engines were based on the BMW M10 inline-4 engines.

All engine variants were available as aftermarket upgrade kit. Not only new BMW engines were modified, but at extra cost used engines were also rebuilt to Alpina specification.

The A0 engine was based on the 1602 engine. It was introduced in 1966 and offered to 1600 owners to upgrade to the performance of the new BMW 1800. Modifications included 2 double Weber 40 DCOE-2 carburateurs and airfilter housing, which added 15hp on the stock engine output. For German approval, installation of an electrical cooling ventilator was mandatory.

The A0 engine was re-introduced in 1975 as aftermarket upgrade kit for the BMW 1502.

The A1 engine was based on the 2002 engine. It was introduced in the 2002 in 1968 and as A1/3 in the E21 320 in 1976. Modifications included 2 double SOLEX C40 ADDHE carburateurs and airfilter housing, which added 15hp on the stock engine output.

The A2 engine was based on the 2002ti engine. It was introduced in the 2002ti in 1969 and as A2/3 in the E21 320 in 1976. Modifications included 2 double SOLEX 45 CCH carburateurs, airfilter housing and exhaust manifold.

The A3 engine was based on the 2002 engine. It was introduced in the 2002 in 1971. Modifications included 2 double SOLEX 45 CCH carburateurs, airfilter housing and exhaust manifold.

The A4 engine was based on the 2002tii engine. It was introduced in the 2002tii A4 in 1973, in the E12 A4/520 in 1974 and E21 A4/3 in 1976. Modifications included custom Alpina fuel injection, airfilter housing and exhaust manifold.

The A4S engine was based on the 2002tii engine. It was introduced in the 2002tii A4S in 1974. This engine did not have German TüV approval and was intended for competition use or export. Modifications in addition to the A4 engine included forged competition grade pistons, as well as lightened and polished connector rods.