a legitimate question about necessity and luxury

This is Episode 2, on the topic of vehicle size.

Cars have grown heavier, taller, and wider over the past two decades. This shift is most visible in the rise of sport-utility vehicles (SUVs), but it affects the whole fleet. The consequences reach beyond tailpipe CO₂. Vehicle mass and geometry influence particulate emissions from tires and brakes, noise exposure, injury risk in collisions, land demand in cities, and the allocation of scarce curb space. The issue is what happens when the default passenger vehicle gets larger than most trips or streets require.

Not only have models increased in size within the model line, but the market has shifted toward larger vehicles overall, with average new-car weight now approaching 2,000 kg in recent datasets, driven by the push toward SUV as new standard.[1] Cities are adjusting to this bulk. Traditional UK bay guidance that once assumed about 2.40 m × 4.80 m is increasingly updated or complemented by wider and longer stalls—around 2.60 m × 5.00 m in new guidance and, in practice with bays up to 2.60 m × 5.50 m in some facilities.[2-4] The trade-off is direct: fitting bigger vehicles either consumes more land or reduces the number of spaces within the same footprint, while on-street, wider bays displace space that could otherwise serve footways, trees, or protected cycle lanes.

We have built a market that celebrates ever-heavier, taller, and wider cars—often SUVs—with luxury features that are downright unnecessary: heated armrests, scarf blowers, cooled cubbies, tablet-scale displays. Regulation has begun to accommodate this bulk. In the European Union, modernised driving-licence rules allow category B drivers to operate alternatively-fuelled vehicles up to 4.25 t, acknowledging battery weight and aiming to ease market uptake.[5] In Europe, SUVs are now roughly 40% of the market by some datasets (and around half by others); in the United States, the SUV share hovers around 53%.[6-7] This is not a trivial styling trend. It carries health risks, safety externalities, social costs, and urban design consequences that radiate far beyond CO₂.  Fleet size influences public health, safety outcomes, and urban form.

We sometimes pretend that electric cars neatly erase all problems because the tailpipe is gone. In many European cities, “non-exhaust” emissions—particles from tires, brakes, and road wear—now dominate traffic-related PM2.5. Brake wear alone can constitute a large share of PM2.5 non-exhaust emissions across cities, and tire wear rises with vehicle mass and power.[8] Recent syntheses put brake wear alone at up to 70 percent of PM2.5 non-exhaust emissions.[9] Tire wear increases with mass and torque; heavier, more powerful vehicles shed more material.[9] That material does not just hang in the air and vanish. Tire and road wear are now a major global source of primary microplastics, with IUCN’s global accounting flagging tires as the largest contributor.[10]

Ultrafine particles (smaller than 0.1 µm) penetrate deeper into the lung and can translocate into the bloodstream and even to the brain; long-term ambient air pollution is associated with elevated dementia risk.[11]  The core mechanism for today’s fleet is simple: heavier vehicles shed more material per kilometre and carry higher kinetic energy at any given speed. This applies to both internal-combustion and battery-electric models. The drivetrain is not the central issue; the mass is.

Noise exposure is another population-level pathway. Chronic road-traffic noise is linked with cardiovascular and metabolic risks, with guideline values recommending average exposure below 53 dB L_den for road traffic.[12] Heavier vehicles tend to increase rolling noise, and high-profile front ends can add low-frequency components. Cardiovascular and metabolic impacts of chronic traffic noise exposure are increasingly documented in European cohorts and medical societies.[13]

Safety for people outside the vehicle is where the geometry shows most clearly. A 2025 peer-reviewed meta-analysis led by researchers at LSHTM and Imperial College found that when pedestrians and cyclists are struck by SUVs or light trucks, odds of death are 44% higher than when struck by passenger cars; for children, the fatality risk increase is 82%, and for children under ten the estimate was about 130%.[14] 

A large, tall front end shifts the primary impact zone upward from the thigh to the torso and head, causing severe primary injuries and reducing the chance that a person is thrown onto the hood rather than down into the vehicle’s path. That change, combined with higher mass, increases lethality in a collision with a pedestrian or cyclist. A 2025 analysis led by researchers at LSHTM and Imperial College found that, in real-world crash data, the odds of a pedestrian or cyclist being killed were 44% higher when struck by an SUV or light truck than by a passenger car; for children, the increase was 82% (and the estimate was about 130% for those under ten).[15-17] High bonnet (hood) lines have crept up across the fleet: Other work links rising bonnet (hood) heights to higher fatality risk for vulnerable road users—each 10 cm of additional bonnet height was associated with a substantial increase in death risk in cited analyses used by European NGOs and research partners.[18-19] The mechanism is not speculative; insurers and safety institutes have separately shown that high, vertical fronts pose greater risk to pedestrians even at lower speeds.[20] Datasets often show that smaller cars are involved in more collisions overall, reflecting exposure and fleet composition. However, when you compare counts, this can yield a paradoxical picture: more total crashes involving smaller cars but similar fatality tallies across small vehicles and SUV, because accidents involving SUV are more likely to be lethal.[21-22] The policy implication is straightforward: lowering speeds and reducing front-end aggressiveness reduce harm at the source, independent of who made a mistake in a particular crash.

Inside the vehicle, the story is complicated by the “arms-race” dynamic. We buy “tanks” because other people drive “tanks,” and the background speed environment remains high; then we point to the resulting crash tests as vindication. Mass helps the occupants of the heavier vehicle in a two-car crash. But this benefit to one party raises risk for the other party—and for pedestrians and cyclists. Studies in Europe report that occupants of a car struck by an SUV face higher serious-injury risk, even as SUV occupants themselves fare better; this is a redistribution of risk, not a net reduction.[23] The good news is that this is not a law of nature. When the fleet is lighter and speeds are lower, excellent occupant safety can be achieved without creating dangerous geometry for others. The levers are known: speed management, compatibility requirements that limit high, stiff front ends, and safety assessments that weight outcomes for people outside the vehicle, not only for those inside. When the fleet is lighter and slower, you can achieve excellent occupant safety without presenting lethal geometry to everyone outside.

Size bleeds into social life. Donald Appleyard’s classic work "Livable Streets" showed how traffic volume erodes neighborhood social networks. Residents on lightly trafficked streets, had many more local social ties than those on heavily trafficked streets. More and larger cars reduce the willingness to linger, chat, cross, and play; the street ceases to be an extension of home.[24] Modern research on “community severance” extends the observation: fast, high-volume traffic and wide carriageways act as physical and psychological barriers that suppress walking and casual crossings.[25] 

Children adapt most. The “normal” of being driven everywhere becomes self-perpetuating. Across German surveys and European networks you see the pattern: high shares of children are chauffeured to school (“Elterntaxis”), and both teachers and parents cite traffic danger as a main reason—even where the danger is exacerbated by the very concentration of cars at the school gate.[26] Independence declines; physical activity declines; informal social worlds shrink. These behavioural adaptations are rational responses to a street environment that prioritises vehicle movement and storage. They can be reversed by reducing speed in mixed areas and by designing streets for legibility and passive safety.

Land use and geometry translate the vehicle choices into city-level costs. A single on-street parking space consumes roughly twelve square metres—about the floor area of a small child’s bedroom—and the average privately owned car occupies a space for 23 hours a day.[27] Most trips also require two spaces (at origin and destination), doubling the footprint demanded by the vehicle. When the fleet gets wider and longer, the area cost grows. Larger vehicles drive designs for wider lanes, larger junctions, and deeper parking bays, as discussed at the beginning of the article. Their footprint and turning radii invite wider lanes, larger junctions, and bigger parking geometries, which, in turn, encourage more paving. The opportunity cost is immediate: narrower footways, less room for protected bike lanes, and fewer trees. More paving hardens microclimates: less evapotranspiration, less shade, more retained heat. The loop closes when a hotter, harsher streetscape nudges more people into climate-controlled cabins, which justifies more vehicle bulk, which demands more paving. Now add “supersizing” to streets already allocated primarily to car movement and storage, and you get the contemporary paradox: a city that is full of cars yet short of mobility. 

That paradox is solvable only by tackling vehicle size and speed while improving alternatives.

Where does this leave cars & SUVs? 

With a legitimate question about necessity and luxury. Many models feature powertrains tuned for rapid acceleration, seating for up to seven, and enormous trunks, while average car occupancy in daily commuting remains close to 1.2–1.4 persons. Large cargo volumes and seven seats are rarely used on typical urban trips and most SUV don't offer all that much interior space given their exterior size either. In this context, more mass and frontal area mean more external cost without corresponding social benefit. The right-sized solution for most urban trips is not a two-and-a-half-tonne vehicle. In everyday city speeds and distances, achieving stability and safety does not require the cars we use today. They require predictable behavior, disciplined speed management, good sightlines, and forgiving geometry for those outside the cabin.

A constructive alternative is to align vehicle classes, street design, and regulation with urban needs. That begins with speed: default 30 km/h limits where modes mix reduce kinetic energy quadratically and cut fatality risk sharply - more on this in a future post. It continues with design: visibility standards that discourage high, blunt fronts; glare controls that align headlamp performance with human vision; and safety ratings that explicitly weight outcomes for people outside the vehicle. 

Small, light city cars are one element within that package, alongside protected-cycle networks and frequent transit, under a calmer speed regime (30 km/h default in mixed urban fabric) as AutoAberKlein is promoting. Properly designed, they reduce harm by construction: less kinetic energy, smaller blind zones, shorter braking distances, and lower non-exhaust emissions per kilometre. It is often reported that small cars are unsafe. That is simply wrong and rather a statement about the current fleet and speed environment, not about the small cars themselves. It is also why a small vehicle vehicle policy, street design, and enforcement must move together. Collisions among small, light vehicles at 30 km/h are not what fill out the trauma statistics, but collisions with heavy, tall, fast vehicles are.

Small cars also leave more road space for protected cycling, wider footways, and trees. For weather protection, the market already offers enclosed microcars (for example, the Silence S04 and peers), and there is room for further development; logistics solutions and micro-transit merit separate treatment (to be addressed in a future piece). For uptime and materials efficiency, hand-swappable, human-manageable battery modules are a practical approach for urban vehicles, avoiding the need to haul surplus energy most of the time. 

None of this requires a culture war. It requires honesty about externalities and a willingness to align street design with the public interest. Individual transport can and must remain, if a compromise is made.

The climate graphs are a warning, yes. But even if you did not care about parts per million of CO₂, the case against supersizing is still overwhelming. Cleaner air. Quieter nights. Safer crossings. More neighbors on stoops. Streets that look like places to be, not pipes to flush vehicles. Human-scale mobility is not a sacrifice. It is the shortest route to a city that works.

Reference list:

[1] US EPA Automotive Trends: average new-vehicle weight at a modern peak (≈1,980 kg in MY2023), illustrating market shift toward heavier vehicles. ([Environmental Protection Agency][3])

[2] British Parking Association update: recommended bay growth to about 2.6 m × 5.0 m. ([britishparking-media.co.uk][4])

[3] AA explainer: legacy UK standard 2.4 m × 4.8 m; note on newer 2.6 m × 5.0 m recommendations. ([AA][5])

[4] Example of larger marked bays in use (2.50 m × 5.50 m, “SUV”/large-vehicle spaces). ([dein-stellplatz.de][6])

[5] European Commission, modernised driving-licence rules: category B permitted to drive alternatively-fuelled vehicles up to **4.25 t**. ([Mobility and Transport](https://transport.ec.europa.eu/news-events/news/commission-welcomes-provisional-agreement-modernised-driving-licences-rules-2025-03-25_en "The Commission welcomes provisional agreement on ..."))

[6] ACEA segment data: SUVs accounted for ~51% of EU new-car sales by 2023; earlier years lower, yielding figures near **40%** in some datasets. ([ACEA](https://www.acea.auto/figure/new-passenger-cars-by-segment-in-eu/ "New cars in the EU by segment"))

[7] IEA, Global EV Outlook 2024: SUVs/pickups/large models exceed 80% of ICE sales in the U.S. and about 50% in Europe; U.S. SUV prevalence commonly reported near **53%** depending on definitions. ([IEA](https://www.iea.org/reports/global-ev-outlook-2024/trends-in-electric-cars "Trends in electric cars – Global EV Outlook 2024 – Analysis"))

[8] EIT Urban Mobility synthesis on non-exhaust emissions: brake wear typically the largest PM2.5 non-exhaust source (≈41–74% across cities). ([eiturbanmobility.eu](https://www.eiturbanmobility.eu/wp-content/uploads/2025/05/41-EIT-Emissions-Report-5a-Digital-1.pdf "non-exhaust emissions in road transport"))

[9] Syntheses on non-exhaust PM: brake wear often the largest PM2.5 non-exhaust contributor; tire wear scales with vehicle mass/torque. ([World Health Organization](https://cdn.who.int/media/docs/default-source/who-compendium-on-health-and-environment/who_compendium_noise_01042022.pdf "Chapter 11. Environmental noise"))

[10] IUCN, Primary Microplastics in the Oceans (2017): tires as a major global source of primary microplastics. ([IUCN Portals](https://portals.iucn.org/library/sites/library/files/documents/2017-002-En.pdf "Primary Microplastics in the Oceans:"))

[11] BMJ 2023 systematic review on ambient air pollution and dementia risk; background on ultrafine particles’ translocation pathways in recent reviews. ([BMJ](https://www.bmj.com/content/381/bmj-2022-071620 "Ambient air pollution and clinical dementia: systematic ..."))

[12] WHO environmental noise guidelines: recommended average exposure for road traffic below 53 dB L_den; nighttime below 45 dB L_night. ([WHO](https://cdn.who.int/media/docs/default-source/who-compendium-on-health-and-environment/who_compendium_noise_01042022.pdf "Chapter 11. Environmental noise"))

[13] DZHK communications on traffic-noise links to cardiovascular/metabolic risks; 2024–2025 summaries. ([dzhk.de](https://dzhk.de/newsroom/aktuelles/news/artikel/verkehrslaerm-ein-neuer-risikofaktor-fuer-herz-kreislauf-erkrankungen "Verkehrslärm, ein neuer Risikofaktor für Herz-Kreislauf- ..."))

[14] Injury Prevention (BMJ) 2025: meta-analysis (LSHTM/Imperial) showing 44% higher fatality odds for pedestrians/cyclists struck by SUVs/LTVs vs cars; 82% for children; ~130% under age 10; institutional summaries. ([injuryprevention.bmj.com](https://injuryprevention.bmj.com/content/early/2025/04/11/ip-2024-045613 "Do sports utility vehicles (SUVs) and light truck ..."))

[15] Robinson et al. (2025), Injury Prevention (BMJ): odds of pedestrian/cyclist death +44% when struck by SUV/LTV vs. car; children +82%; under-10 ~+130%. ([injuryprevention.bmj.com](https://injuryprevention.bmj.com/content/early/2025/04/11/ip-2024-045613 "Do sports utility vehicles (SUVs) and light truck ..."))

[16] LSHTM press summary of the same meta-analysis; estimates of SUV involvement shares in crashes (≈45% US; ≈20% Europe). ([LSHTM](https://www.lshtm.ac.uk/newsevents/news/2025/being-hit-suv-increases-likelihood-death-or-serious-injury "Being hit by an SUV increases the likelihood of death or ..."))

[17] Newswire summaries of the peer-reviewed study (EurekAlert, 2025). ([EurekAlert!](https://www.eurekalert.org/news-releases/1081887 "Being hit by an SUV increases the likelihood of death or ..."))

[18] Transport & Environment (2024–2025): rising bonnet heights linked to higher VRU fatality risk; proposals for bonnet-height caps. ([The Guardian](https://www.theguardian.com/world/2025/jun/11/ever-rising-height-car-bonnets-suv-threat-to-children-report "Ever-rising height of car bonnets a 'clear threat' to children, report says"))

[19] IIHS: higher, more vertical fronts pose greater pedestrian risk, independent evidence base. ([IIHS Crash Testing](https://www.iihs.org/news/detail/vehicles-with-higher-more-vertical-front-ends-pose-greater-risk-to-pedestrians "Vehicles with higher, more vertical front ends pose greater ..."))

[20] IIHS experimental crash analyses comparing SUVs and cars at various speeds. ([IIHS Crash Testing](https://www.iihs.org/news/detail/new-study-suggests-todays-suvs-are-more-lethal-to-pedestrians-than-cars "New study suggests today's SUVs are more lethal to ..."))

[21] Belgian study summary via ETSC: serious-injury risk decreases for SUV occupants but increases for occupants of the other car in SUV-car crashes. ([ETSC](https://etsc.eu/suvs-and-pickups-make-the-roads-less-safe-for-car-occupants-pedestrians-and-cyclists-belgian-study/ "SUVs and pickups make the roads less safe for car ..."))

[22] Belgian study summary via ETSC: serious-injury risk decreases for SUV occupants but increases for occupants of the other car in SUV-car crashes. [ETSC](https://etsc.eu/suvs-and-pickups-make-the-roads-less-safe-for-car-occupants-pedestrians-and-cyclists-belgian-study/)

[23] IIHS long-run fatality facts showing changing distribution of fatalities by vehicle type as SUVs/pickups grow in share.

[24] Appleyard’s “Livable Streets” findings summarized by PPS and others: heavy-traffic streets show sharply fewer local social ties. ([Project for Public Spaces](https://www.pps.org/article/dappleyard "Donald Appleyard"))

[25] Review literature on “community severance”/barrier effects (SpringerOpen 2022). ([SpringerOpen](https://etrr.springeropen.com/articles/10.1186/s12544-021-00517-y "Disentangling barrier effects of transport infrastructure"))

[26] German surveys on “Elterntaxi” prevalence and perceived hazards (ADAC Stiftung and allied summaries, 2022–2025). ([ADAC Stiftung](https://stiftung.adac.de/umfrage-sicherer-schulweg/ "Umfrage \"Sicherer Schulweg\""))

[27] VCD materials: a standard parking space ≈12 m²; car occupies it most of the day. ([vcd.org](https://www.vcd.org/artikel/12qmkultur-2022 "Unser 12qmKULTUR-Jahr 2022"))