If certain suppliers have their way, not all future hybrids will have large battery packs, or the ability to drive only on electric power for appreciable distances.
But they could still have a significant impact on fuel economy.
That's because they'll rely on beefed-up electrical systems to take some of the load off their internal-combustion engines.
Delphi plans to unveil a new 48-volt electrical system at the 2016 Consumer Electronics Show (CES) in January, something it believes can help increase fuel economy, according to Ward's Auto.
It could prove attractive to carmakers like Ford, which is expected to devote a large chunk of a recently-announced $4.5 billion spending program on electrified vehicles to 48-volt mild hybrids.
The prototype Delphi plans to unveil at CES will include a 48-volt lithium-ion battery, controllers for the battery and powertrain, a DC/DC converter, and an electric turbocharger that would be attached to an internal-combustion engine.
BMW M3 M Performance exhaust
Power from the battery is fed to an electric motor/generator, which starts the engine and helps the car get moving at low speeds.
The DC/DC converter steps power down to 12 volts to run the car's accessories, which still use the 12-volt electrical system that's been standard for half a century now.
Delphi claims its system can offer 70 percent of the fuel-economy benefit of higher-voltage mild-hybrid systems, but at just 30 percent of the cost.
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It did not offer specific efficiency figures, but said the results of fuel-economy economy testing will be released at CES.
The company believes systems like this will soon become necessary for carmakers to meet stricter global emissions standards.
It expects the 48-volt system to be in production by 2017, but doesn't think demand will pick up until around 2020, when carmakers will feel the pressure of efficiency standards more acutely.
Officials expect Europe to take the lead in adopting 48-volt electrical systems, because of standards set to take effect by 2021. China won't be far behind, they argue.
And U.S. Corporate Average Fuel Economy (CAFE) standards requiring a fleet average of 54.5 mpg (closer to 40 mpg on window stickers) by 2025 should lead to significant demand here, Delphi believes.
At first, many cars will retain their 12-volt electrical systems to power accessories, Delphi predicts.
But these dual electrical systems could eventually be merged, and the 48-volt system's lithium-ion battery pack could be used to power those accessories.
Other items--such as coolant pumps and air-conditioning units--that are typically driven by the engine could also be switched over to 48-volt electrical power.
That would eliminate some parasitic losses, potentially leading to even greater gains in fuel efficiency.