If news from Japan is correct, Honda and General Motors are in the final stages of a proposed tie-up to co-develop plug-in hybrids.

The two automakers since Summer 2013 have been collaborating on hydrogen fuel cell vehicle technology for which they are the top two patent holders.

A move to increase the alliance – in PHEVs and also autonomous tech – is now in the offing says the English-language version of The Yomiuri Shimbun.

Without naming the source of its otherwise unequivocal report, the publication says that by sharing resources Honda and GM stand to undercut competitors’ prices while staying ahead of tightening regulations.

Noted also was Honda reportedly credits GM with being further along in PHEV development.

“Honda was originally planning to release PHVs on its own in the United States in 2018,” says the report. “With the partnership, the company aims to add GM’s know-how regarding PHV development to its own eco-cars, because GM is said to be more advanced in the field.”

SEE ALSO: Honda Confirms Plug-In Hybrid With 40-mile EV Range By 2018

Could we thus within a couple years see a Honda plug-in hybrid with a discrete badge that says Voltec Inside? This is unknown, but Honda has promised a 40-mile range PHEV by 2018 and the report now says plans may have shifted.

To date, Honda has been mainly experimental with production battery electric and plug-in hybrid cars. Its limited-market Fit EV is now discontinued, and the 2014 Accord PHEV was also limited market and also came and went.

2014 Accord PHEV.

2014 Accord PHEV.

The Accord PHEV had but 13 miles EV range because it was essentially an add-on measure with 6.7-kwh battery occupying much room in the trunk.

In October 2014, Honda launched its non-plug-in hybrid Accord based on the same architecture albeit with much smaller battery and no significant EV range.

Notable are these cars’ powertrains are not at all inferior with regard to energy efficiency to what General Motors has in the Volt.

On the contrary, the midsized Accord PHEV’s 115 MPGe (29 kwh/100 mi) clearly beats both the compact first-generation Volt and second-generation Volt in ability to utilize battery energy for propulsion. Their dual-motor hybrid systems are actually gee-whiz technology worthy of a Popular Science feature using the motors in lieu of an actual transmission.

Note the larger Accord PHEV clearly edges out Voltec's efficiency even for the second-gen Volt.

Note the larger Accord PHEV clearly edges out Voltec’s efficiency even for the second-gen Volt.

Last month Honda told HybridCars.com that while the 47-mpg Accord Hybrid will sit out 2016, an improved version is due the year following.

So would Honda scrap its system for a new plug-in hybrid and go to what GM has? the Accord plug-in hybrid is a blended PHEV, and a firm press of the accelerator would always kick on the gas unlike with the unique “extended-range electric” Volt.

The 2015 Volt could go an unofficial 40 miles – Honda’s target by 2018 – and the 2016 is rated for 53. The Chevrolets also compromise interior room with a large T-shaped battery dominating the center tunnel front and back, a concession Honda may not be willing to make and instead a PHEV-optimized design may be what it has in the works.

Certainly GM has learned lessons it could pass along to Honda, but assuming the two do collaborate as reported, a primary driver may be less need for respective intellectual property, and more to save costs.

2017 Chevy Bolt mule. Would it make as much sense or more for Honda to tap GM and its LG-Chem connection for its expertise in BEVs?

2017 Chevy Bolt mule. Would it make as much sense or more for Honda to tap GM and its LG-Chem connection for its expertise in BEVs?

“The companies believe their tie-up can shorten the development period and enhance their advantage in price negotiations with auto parts makers by boosting the volume of their procurement,” says the report. “The two companies are considering the joint manufacture of PHVs and FCVs as well, in addition to their development.

But for now, this is no more than a rumor. The Yomiuri Shimbun did not cite its source as it declared final stages of negotiations between Honda and GM, and neither carmaker has announced anything definitive.

However also, secrecy is part and parcel of this business, and the need for some form of cost/IP sharing is certainly in place between the two companies already partnered on FCVs.

“I know of no reason to affirm or dispute the Honda-GM tieup, but it seems reasonable,” said Michigan-based analyst Alan Baum. “It would be even more credible if LG Chem was going to supply systems to both.”

If we learn more, we’ll pass it along.

The Yomiuri Shimbun via InsideEVs