Cars have grown 1.2cm longer, 0.5cm taller and 0.5cm wider each year on average since 2000, analysis of new vehicles sold in Europe has found, in what green groups call “relentless carspreading”.

The increase in size, which leaves people more likely to be killed in a crash and increases emissions that hurt lungs and heat the planet, has progressed at a roughly steady rate for two and half decades even as family sizes have fallen, the campaign group Transport & Environment (T&E) found.

Car bloat is frustrating drivers, too, with cities set to lose 8.5-14% of on-street parking by 2040 if the historical trend continues unchecked, the analysis found. London and Berlin are each set to lose about 100,000 parking spaces.

The findings come as research shared exclusively with the Guardian shows potential SUV buyers are undeterred by warnings that they are more likely to kill pedestrians.

Lucien Mathieu, an analyst at T&E and lead author of the report, said the “dramatic trend” held serious consequences for public safety and the erosion of urban space.

“This relentless carspreading highlights one critical question: where do we stop?” Mathieu said. “The linear trend is so clear.”

The authors modelled a scenario in which cars supersize at their current rate until 2040, as well as one of “right-sizing” fleets by bringing average car sizes back to 2015 levels.

Compared with the right-sizing scenario, current trends would lead to an extra 2,600 vulnerable road users dying in crashes each year by 2040, 79 of them children. The extra resources needed to move the cars would equate to an extra 100m barrels of oil imports and 22.5 terawatt hours of electricity.

The findings do not consider the extra deaths from air pollution resulting from burning more fossil fuels or more extreme weather from additional climate breakdown.

Brian Caulfield, a transport researcher at Trinity College Dublin, who was not involved in the report, said it highlighted “several striking points of concern” if current rates of vehicle growth persisted.

“When viewed through a climate lens, larger vehicles require more energy, regardless of whether they are fossil fuelled or electric,” he said. “The research suggests this added demand could be equivalent to the output of an extra 1,500 offshore wind turbines. Globally, energy grids are already under stress from the electrification of heating, transport, and datacentres; the projected increase in energy demand from larger vehicles will only compound these issues.”

The projections relied on research from Belgium that found a 10cm increase in bonnet height results in a 27% higher risk of death for vulnerable road users. For children, they relied on research from the US that found such an increase in size led to an 81% increase in a child dying.

The authors recommended capping bonnet heights and car widths, changing taxes to discourage people from buying bigger vehicles, and tightening vehicle standards so they considered the visibility of young children from the driver’s seat.

Hannah Budnitz, a researcher at the transport studies unit of the University of Oxford, who was not involved in the report, said: “Larger vehicles are more dangerous to other road users, take up more space and use more resources, both when they’re manufactured and to keep them in motion.” She said the projections were “probably conservative” because they did not factor in vehicle weight, which increases resource consumption and leads to more wear and tear on roads.

She added: “In many places, parking bays are marked and are not being re-marked gradually in the way the scenario suggests, meaning that larger vehicles can end up taking up two spaces by default – or overflowing into space for other road users.”