The only way to meet future CO2 targets is with electrification, analysts said, and SUVs have both drawbacks and advantages. On the plus side, relatively boxy and spacious body types make it easier to fit batteries under the floor and electric drivelines around transmissions and rear axles.
"If you wanted to hybridize an existing car it's far easier to do it in an SUV," said Oliver Petschenyk, a powertrain analyst at LMC Automotive. "There is greater package space, but perhaps more significantly the body in white crash structure is designed to handle more weight."
This means that SUVs require fewer modifications than sedans to prevent injuries to occupants in a crash from a battery that can weigh several hundred kilograms, he said.
Another less-obvious advantage for SUVs is that they have a built-in pricing buffer against some of the costs of electrification, analysts said.
"Especially at the higher price points, you can absorb the prices for a plug-in hybrid or electrification," IHS's Urquhart said.
In other words, SUVs might be a better canvas to pursue electrification developments while preserving profits than low-margin small or compact cars.
For the majority of SUVs "electrification" will not mean full-electric versions, but rather a spectrum of solutions from 48-volt mild hybrids to conventional hybrids and plug-in hybrids, analysts said.
"The plug-in hybrid SUV offerings, especially for premium brands, will really intensify," said Al Bedwell, director of global powertrain at LMC, as automakers seek to take advantage of emissions "supercredits" for vehicles that emit less than 50g/km of CO2, a figure many plug-in hybrid SUVs can reach.
For example, Peugeot lists emissions for its plug-in compact 3008 as 29g/km. "We are also seeing a mass rollout of 48-volt mild hybrids, which can deliver up to 10 percent CO2 savings," Bedwell said. Another benefit of electrification comes from so-called "e-axles," which can be used to provide a four-wheel-drive system without the need for heavy and intrusive driveshafts running through the passenger compartment.
On the other hand, there is no getting around the fact that SUVs and crossovers are heavier and less aerodynamic than equivalent sedans, reducing the range of full electric and plug-in models, as well as limiting efficiency gains for mild and conventional hybrids.
"The biggest negative with SUVs becomes rolling resistance and aerodynamic drag due to larger wheels and frontal mass, which can't really be improved without a downsize," LMC's Petschenyk said.
It is this inescapable fact that is putting automakers under pressure from environmental advocates. They say that automakers' complaints about difficulties meeting emissions targets ring hollow when, at the same time, they are pushing sales of inefficient SUVs and crossovers.
"It's just a question of physics," said Florent Grelier, an engineer at T&E. "Crossovers and SUVs are heavier and less aerodynamic." Grelier's group says that increasing SUV sales are largely responsible for the recent rise in overall vehicle CO2 emissions across Europe following years of decline. This is increasing the gap automakers must close by 2021.
A decline in sales of diesel engines, which emit less CO2 than equivalent-sized gasoline models, is only part of the reason for the increase, Grelier said. "Our report showed that the impact of increasing sales of SUVs on CO2 levels is 10 times more impactful on average CO2 levels than the drop in diesel," he said.
Nonetheless, Grelier said he expected European automakers to hit their CO2 targets, using a variety of regulatory and technological tools at their disposal.
Even with 100 SUV and crossover models already on the European market, automakers are still creating new niches within the niche. "We are just arriving at saturation," said Munoz of JATO. "Most brands are present in the small and compact segments."
The next trend may be coupe-style SUVs, a body type pioneered by BMW with the X6. Toyota has found success with the C-HR, and Porsche has introduced a coupe version of the Cayenne. Renault has debuted the Arkana, a coupe version of the Kadjar, on the Korean and Russian markets.
Some brands are also doubling up in the SUV segments. Ford has both the Puma and the EcoSport small SUVs in its lineup, with the Puma being the sportier and higher-priced model. Similarly, the Volkswagen T-Roc sits above the T-Cross in the small segment (or below the larger Tiguan in the compact segment). Jeep offers both the Compass and Renegade compact models; Land Rover's Velar and the Range Rover are similarly sized but with different characters. "What we are seeing now is that reference models have been established," Munoz said, "but automakers are adding derivatives to attract new customers."
But there could be a point of diminishing returns, analysts said. Munoz pointed to the new Mazda CX-30 as an example of a model that could "confuse" buyers. "Is there really a need to have another SUV between the CX-3 and CX-5?" he said. "It could take sales from both models. On the other hand, it might bring in new ones."