Range anxiety remains one of the biggest obstacles to widespread electric-car adoption, but two of the main ways to increase range are proving expensive, according to a new report from Lux Research.

Bigger battery packs cost more, but reducing weight may not be cost effective, according to the report, which established a threshold of less than $5 per kilogram of weight saved for cost effectiveness.

But reducing weight often relies on different, more expensive materials. The reported cited use of high-strength steel and aluminum in vehicle structures, as well as carbon fiber for seats, as possible areas for automakers to consider.

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Lux is more optimistic about battery technology. While battery packs make EVs relatively heavy compared to internal-combustion cars, the report said use of regenerative braking, along with anticipated improvements in battery energy density, mean electric cars don't require more lightweighting than their internal-combustion counterparts.

Battery tech also has more "runway" than materials tech, meaning it has more potential for cost reductions, the report said. Increased energy density itself could also do some of the job of lightweight materials, by eliminating the need to make battery packs bigger to achieve a given range, analysts noted.

Vehicle mass/kwh vs BEV range - Lux Research, November 2020

So while weight reduction has been crucial to achieving gas-mileage gains for internal-combustion cars, by 2030 electric cars will be less reliant on lightweighting, and more on battery-tech improvements, the report predicted.

That would certainly be the more convenient route for automakers—especially once they've exhausted other means like aerodynamics, tires, and the rest of the propulsion system.

Aptera has gained much attention for its weight reduction and hyper-efficient vehicle concept, but designs like this may not offer the same level of safety as conventional passenger cars.

Meanwhile, federal fuel-efficiency rules are likely making vehicles larger. That's because larger vehicles have lower fuel-economy targets under the Corporate Average Fuel Economy (CAFE) framework.

Most will agree that outside of the realities of crash compatibility, the way to boost efficiency is in lighter cars that carry more people.

And in terms of battery weight per kilowatt-hour, at least one analysis suggests that smaller batteries in hybrids would make better use of relatively scarce battery cells. Hybrids would, however, still be carrying around some extra weight all the time—that of an internal-combustion engine and all that goes with it.