Tiny briefcase engine boosts EV range beyond battery power

Automotive supplier Horse Powertrain continues to push the next generation of plug-and-play range-extended hybrid solutions. Sized "no larger than a briefcase," the all-n...

Sep 06, 2025

It's bigger than the average briefcase, and certainly not "briefcase-shaped" compared to any briefcase we've seen, but the C15 is designed to be small and sleek enough to easily integrate into many EV classes and layouts

Automotive supplier Horse Powertrain continues to push the next generation of plug-and-play range-extended hybrid solutions. Sized "no larger than a briefcase," the all-new C15 four-cylinder engine-generator is designed to slide into all-electric vehicle platforms with little to no modification necessary, bringing an immediate high-efficiency range boost with or without turbo.

Horse has always struck us as a company just over the right side of the thin wire fence dividing genius from insanity. Had it debuted a couple of years earlier, when the automotive world had its head down toward going 110% all-in on electric vehicles, it would have struck us as a bit insane, or at least "too little, too late." But having ramped up at a time when governments and automakers worldwide are rethinking those EV plans and timelines, it seems to be perfectly positioned for a renaissance in hybrid technology. For now, at least.

Regardless of what anyone else thinks, though, Horse remains convinced that the future of electrified vehicles is hybrid, and it continues expanding its lineup of range extender solutions engineered to support that future. At the start of the year, it began production on a compact electric motor meant to fit to ICE-powered vehicles for improved efficiency and emissions performance. Now it presents something of an opposite counterpart: an ultra-compact ICE designed to slide into all-electric models to boost range and add refueling capability to complement battery charging.

One way or another, Horse wants automakers to find just the right balance of electric and combustion drive power.

*Horse Powertrain goes the other direction from its electric motor lineup, developing an ICE generator designed to hybridize electric vehicles for more range, less anxiety*

First things first: We just have to put some numbers around Horse's claim of briefcase-level sizing. The company is kind enough to list dimensions out in this week's sneak peek, speccing the C15 base unit at 19.7 x 21.7 x 11 in (50 x 55 x 28 cm).

In a modern workspace defined by remote work and digital product, I can't say I've ever had a reason to carry an actual briefcase so I have nothing around to physically compare those numbers against. Luckily, that same wide open digital space affords access to a boundless collection of numbers with which to compare. Taking a quick look around at a couple of actual briefcase models suggests that Horse is a little overly optimistic as to just how small it's managed to package the C15. Perhaps, it, too, hasn't held an actual briefcase in decades.

We weren't shocked to see that it had played a little fast and loose with its comparison in trying to craft a crisp, clear image of a small, lightweight combustion-generator. We found that actual briefcases, of both hard and soft varieties, over at Briefcase.com (still a thing!) and other retailers commonly ranged between 16 to 18 in (41 to 46 cm) long by 12 to 14 in (30 to 36 cm) high by 3 to 8 in (8 to 20 cm) thick. And that includes the big lugs in Briefcase.com's "Large" category (no XL category listed).

So clearly the C15 is a bit "larger than a briefcase," but we suppose it's close enough in a ballpark sorta way, especially since we're talking about a combination engine, generator, inverter, and exhaust and cooling hardware – a package we wouldn't have expected to size anywhere close to a briefcase at all.

But we'll all need to dissociate from any visions of black-suited Horse reps toting C15 engines around the garage in attaché cases.

Horse will show the C15 at next week's IAA Mobility Munich show

In reality, the C15 will comprise a full family of drop-in range-extenders, and those afore-listed dimensions belong to the most modest of the initial units. The Euro 7-compliant naturally aspirated 1.5-liter four-cylinder puts out up to 70 kW (94 hp) of power to directly charge the vehicle's traction battery via its integrated generator and maintain charge level. It is not connected to the wheels so never provides direct drive power, allowing it to operate steadily in the optimal rpm range to further increase efficiency, cut emissions and deliver smooth performance.

The 70-kW version will be aimed at Europe's B and C vehicle segments, and Horse will also tack on a turbocharger to up power to 120 kW (161 hp) for larger D-segment and light commercial EVs. It doesn't list the dimensions of that one, so we'll spec it at "definitely larger and lumpier than a briefcase."

Aimed at integration by automakers and powertrain OEMS, the C15 units are designed to be installed horizontally or vertically and fit into the front or rear of the vehicle. The idea is to give manufacturers plenty of flexibility in transforming battery electric vehicle (BEV) platforms into range-extended series hybrids.

Beyond simply increasing range at the vehicle level, the C15 is also designed to allow OEMs to develop platforms around smaller battery packs, cutting overall weight and cost without an accompanying decrease in total driving range.

"Range-extended EVs (REEVs) are the fastest-growing powertrain category in many global markets," said Horse CEO Matias Giannini. "The Horse C15 range extender solution offers OEMs a straightforward and cost-effective way to tap into this opportunity and adapt their native BEV platforms into REEVs. We believe demand for REEVs will continue to grow; Horse C15 will play a critical role in this transition."

Like the Future Hybrid Concept powertrain Horse previewed at Auto Shanghai in the spring, the C15 is designed around multi-fuel capability. It can be powered by gasoline, ethanol and methanol flex fuels, and synthetic fuels, giving manufacturers another flexible tool in making vehicles cleaner and more efficient overall.

Horse plans to give the industry its first full look at the C15 series at IAA Mobility 2025, which starts in Munich on Monday. We'll see if the company doesn't have more details and performance estimates once the C15 makes its full premiere.

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