City Bus Propulsion and the EU Zero-Emission Mandate

City bus propulsion in the European Union is now partly a regulated choice, but the regulation binds manufacturers’ fleet shares, not operators’ purchases, and it stops at the boundary between a city bus and a coach.

The obligation, and who carries it

Regulation (EU) 2024/1610, published in the Official Journal on 6 June 2024 and applicable from 1 July 2024, inserted Article 3d into Regulation (EU) 2019/1242. For the vehicles in the fourth column of the table in point 4.2 of Annex I — the column headed “Urban buses” — “manufacturers shall comply with the 90 % and 100 % minimum shares of zero-emission heavy-duty vehicles in their fleet of new heavy-duty vehicles in accordance with point 4.3.2 of Annex I.”

Point 4.3.2 gives the schedule: zero for reporting periods before 2030, 90 % for 2030–2034, 100 % for 2035–2039, and 100 % as from 2040.

The duty falls on the manufacturer, over its own registrations in a reporting period, not on a city or an operator. But it is not settled bus by bus. Point 4.1 of Annex I folds the mandate into a single specific CO2 emissions target for the whole passenger-carrying category, T(M) = T(MCO2) + T(MZE), and point 5.2 computes emission credits and debts at that same category level, so an urban bus shortfall can in principle be carried by over-performance on coaches. Nor is it a hard annual cliff: Article 7 caps total emission debt at 5 % of the specific CO2 emissions target multiplied by vehicle count, clears remaining debts in the reporting periods of 2029, 2034 and 2039, and lets credits count for seven years. Article 8 sets the excess premium at EUR 4,250 per gCO2/tkm.

Zero-emission has a numeric definition: the amended point 11 of Article 3 requires no internal combustion engine, or one emitting not more than 3 g CO2/tkm or 1 g CO2/pkm. A diesel or gas hybrid does not reach that threshold, so hybridisation is not a compliance route.

Not every vehicle counts: Article 3a(5) exempts from the CO2 reduction targets vehicles registered for civil protection, fire services, forces maintaining public order or urgent medical care where a Member State so indicates in registration, and vehicles registered for the armed services fall outside the Regulation where a Member State does not report them.

A separate instrument acts on the buyer. Directive 2009/33/EC sets minimum procurement shares for clean M3 buses in public contracts, half to be met by procuring zero-emission buses. Germany’s share was 45 % for contracts awarded between 2 August 2021 and 31 December 2025, and is 65 % for the second reference period to 31 December 2030; in the first period only, the zero-emission half fell to a quarter where more than 80 % of the buses concerned were double-deckers.

Where the line between urban bus and coach is drawn

The urban bus sub-groups are named in Annex I: 31-LF, 31-L1, 31-DD, 33-LF, 33-L1, 33-DD, 35-FE and 39-FE. They map to the vehicle groups of Regulation (EU) 2017/2400, which classifies a heavy bus by axle count and body code and, for low-entry bodies, by the class of vehicle under paragraph 2 of UN Regulation No 107.

R107 draws the distinction that matters. Class I means vehicles “constructed with areas for standing passengers, to allow frequent passenger movement”. Class II means vehicles “constructed principally for the carriage of seated passengers”, with standing only in the gangway or an area no larger than two double seats.

The urban bus column takes the two- and three-axle rigid buses built on low-floor body codes, single and double deck, plus every articulated bus of groups 35 and 39 — low-floor and low-entry, Class I and Class II alike, since 35-FE aggregates 35a, 35b1, 35b2 and 35c.

Everything else sits in the third column, headed “Coaches and Class II Low Entry Buses”: the high-floor groups 32-C2, 32-C3, 32-DD, 34-C2, 34-C3 and 34-DD, plus the low-entry Class II sub-groups 31-L2 and 33-L2. Those carry CO2 emissions reduction targets under Article 3a read with Annex I point 4.3.1 — 0 for 2025–2029, 43 % for 2030–2034, 64 % for 2035–2039 and 90 % as from 2040 — and no zero-emission share at all. Article 3a(1) itself states only the headline 45 % and 65 %; its paragraph 2 sends the sub-groups to point 4.3, where the coach figures sit. Recital 36 says as much: “regional and long-distance buses and coaches” remain subject to the CO2 targets for heavy-duty vehicles.

Body, not route, decides treatment, and among low-entry vehicles the R107 class is the whole of the split: a two-axle low-entry Class II vehicle is 31-L2 and falls outside Article 3d, while the same two-axle low-entry vehicle in Class I is 31-L1 and falls inside.

What the registration data shows

ACEA recorded 38,238 new EU bus registrations in 2025, up 7.5 %, with electrically chargeable vehicles at 23.8 % of the segment, hybrid-electric at 7 % and diesel at 62.1 %. In the first half of 2026, registrations reached 22,590 units, up 22.7 %; the electrically chargeable share rose to 27.7 %, diesel held 58.2 % and hybrid-electric 6.1 %.

Those are not urban bus shares. ACEA reports buses as one segment, without splitting city buses from interurban buses and coaches. The gap showed in 2022: ACEA put electric at 12.7 % of new buses, while recital 35 records zero-emission urban buses “already represented around a quarter of all urban buses sold in the Union”.

Diesel and hybrid

Diesel’s advantage is infrastructural: refuelling takes minutes, one fuel island serves a whole depot, and range does not depend on the route a vehicle draws that day. No line profile constrains it, which is why diesel holds low-frequency and peak-only work.

Hybrid drive suits dense stop-start work, where braking energy is recovered most often, and needs no depot change. It does not count towards Article 3d, but remains available in the coach and Class II low-entry sub-groups, where the instrument is a CO2 target.

Battery-electric

Two charging architectures produce two different depots. Overnight depot charging uses a CCS2 plug: Daimler Truck rates the eCitaro at up to 150 kW on CCS and up to 300 kW by pantograph, with NMC4 packs of 111 kWh each, four to six for the solo bus and four to seven for the articulated eCitaro G, up to 777 kWh. Solaris specifies the Urbino 12 electric with a ZF CeTrax 220 kW drive, Solaris High Energy batteries of 420 kWh, plug-in charging up to 260 kW and pantograph charging up to 450 kW.

Opportunity charging moves the transfer to the terminus, and the interface there is already binding law. Annex II to Regulation (EU) 2023/1804 provides that a contact interface automated device for electric buses on conductive recharging in mode 4 “shall be equipped at least with mechanical and electrical interfaces, as defined in the standard EN 50696:2021”, in four arrangements: an infrastructure-mounted pantograph, a roof-mounted or underbody device on the vehicle, or an infrastructure device connecting to the side or roof. Article 3d(2) directs the Commission to add common technical specifications for that interoperability by implementing acts.

The depot is the binding constraint: the whole fleet parks on one site and draws at once. Regulation (EU) 2023/1804 required each urban node to have publicly accessible heavy-duty recharging of at least 900 kW aggregate by 31 December 2025 and 1,800 kW by 31 December 2030 — but that is public infrastructure, not depot supply. No EU instrument obliges anyone to deliver a grid connection to a bus depot, and that lead time routinely exceeds the vehicle order’s.

Trolleybus and in-motion charging

A trolleybus has no internal combustion engine, so it meets the Article 3d definition directly, and the modern version is not purely wired. Solaris specifies the Trollino 12 with a 175 kW traction motor, a Solaris High Power battery of 58 kWh and an automatic pantograph. In-motion charging is documented separately by the manufacturer: the batteries charge while the vehicle is connected to the overhead wire, giving, depending on capacity, “up to several dozen kilometres” off catenary.

That fits a city that already owns overhead line and substations. Where no catenary exists, the cost of building one keeps the option off the list.

Hydrogen fuel cell

Fuel cells answer the case where daily distance on a single shift, or depot electrical capacity, is the limit. Solaris specifies the Urbino 12 hydrogen with a 70 kW fuel cell, an electric axle carrying two integrated 125 kW motors, and Type 4 composite tanks of 1,560 l total (5 × 312 l), at 19,200 kg GVW. CaetanoBus specifies the H2.City Gold with a 60 kW Toyota fuel cell stack, a 180 kW Siemens permanent-magnet synchronous motor, Type 4 tanks of 5 × 312 l holding a maximum 37.5 kg at 350 bar, a 44 kWh LTO battery, refuelling in under nine minutes to SAE J2601-2 and SAE J2799, and consumption from 5.5 kg/100 km. On range that datasheet gives two figures: the specification table states an estimated more than 450 km depending on operating conditions, while a brochure headline in the same PDF advertises up to 400 km.

The power figures are the design tell: a 60 to 70 kW stack against a 180 to 250 kW drive means the stack charges a buffer battery rather than driving the wheels.

The depot requirement is a 350 bar dispensing installation with compression and storage. AFIR’s public network is specified at a different pressure — stations of at least one tonne per day with a 700 bar dispenser, no more than 200 km apart along the TEN-T core network by 31 December 2030, and one in each urban node — so a bus fleet builds its own.

What 2030 changes for a buyer

From the 2030 reporting period the catalogue narrows for the urban bus column, because each manufacturer must find 90 % of those registrations from zero-emission product — softened by the category-M arithmetic and banked credits, not removed by them. It does not narrow for low-entry Class II vehicles or coaches, which carry no zero-emission share at any date in the current text. Residual values follow.