Mercedes-Benz is betting big on plug-in hybrids. The German automaker will have 20 of them in its global lineup by the end of 2020, although many will not be available in the United States.

In a press release, Mercedes said plug-in hybrids will be a "key bridging technology" to all-electric cars.

Mercedes announced plans for a third-generation plug-in hybrid system, wearing EQ Power badging, in late 2018. The automaker has sought to increase electric range, a weak point of its previous plug-in hybrids.

The new plug-in hybrid powertrain for larger vehicles teams gasoline engines with a 9-speed automatic transmission, and larger battery packs than before.

This version is used in the latest GLC350e crossover, which is expected to be sold in the U.S.

Mercedes-Benz GLA250e, CLA250e, and CLA250e Shooting Brake

Mercedes is also expanding availability of plug-in hybrid powertrains to its compact models. These are less likely to reach the U.S.

The compact models use a 15.6-kilowatt-hour battery pack. The CLA250e model is rated at 43 miles of range on the European WLTP testing cycle, which is a bit more optimistic than the U.S. EPA testing cycle.

If cars are frequently plugged in, Mercedes claims plug-in hybrid powertrains can reduce carbon dioxide (CO2) emissions by 40%, using the current electricity-generating mix in Germany. That increases to 70% if cars are charged using renewable energy, according to Mercedes.

But plug-in hybrids only provide that benefit if owners are fastidious about charging. The advantage disappears if cars aren't plugged in.

Meanwhile, Mercedes has repeatedly delayed the U.S. launch of its all-electric EQC crossover.

The EQC, which is already on sale in Europe, was originally scheduled to launch in the U.S. in mid-2019. Mercedes pushed the launch back to early 2020, and then first quarter 2021. The automaker has said it wants to focus on European sales for the time being.