Mercedes-AMG has the basis of a good performance hybrid system in the E Performance plug-in hybrid powertrain of the latest Mercedes-AMG C63

The high-voltage battery pack is relatively light and energy-dense but is also effectively cooled and thermally robust, so lots of intensive charging and discharging doesn't seem to overheat it. The two-speed rear-axle drive also seems to allow the electric motor to feed in plenty of torque throughout the speed range.

New 2024 Mercedes-AMG E63 swaps V8 for straight-six PHEV

Teamed with the right engine, it could all still amount to a convincing, emissions-savvy super-saloon. But that engine needs to be more exciting than the C63's four-pot, as well as richer to listen to, in what will be a six-figure purchase. 

It needs to rev more freely than AMG's M139 2.0-litre unit; and, in my book at least, it wouldn't matter if it had a peakier power delivery, with the hybrid system there to cover for any low-end deficiencies.

It's a vain hope to expect Affalterbach to go back to high-revving atmo engines like the old M156 6.2-litre V8, not least because they would never be emissions-compliant these days. But a straight-six turbo should certainly sound better than the C63's four-cylinder and rev more keenly.

So the next Mercedes-AMG E63's mechanical recipe is already sounding more appealing that its little brother's. Being a bigger and heavier saloon already than the hot Mercedes-Benz C-Class should also help disguise the hybrid system's weight penalty - and having adaptively damped air suspension (the C63 runs on steel coils) should allow AMG better ways to deal with the added mass.

All things being equal, nobody would vote to have heavier, more expensive and more complicated performance cars. But if that's the way they have to go in order to continue to exist (in a volume-selling sense, at the very least), then striking just the right compromise of low emissions and high drama with them will be absolutely key.