How We Calculate These Figures
Every figure on this site comes from CSO Department of Transport data, with the formula shown so you can check it.
Vehicles per 1,000 people
Vehicles per 1,000 = (private vehicle fleet ÷ population) × 1,000
The fleet count is the latest month's private-vehicle snapshot from CSO table DOTM08. The population is each county's 2022 census figure (CSO table FY001) — there is no annual county-level population estimate published, so this denominator does not move between census years even as the fleet count does.
EV share and fuel mix
Fuel mix is each county's private-vehicle fleet split by fuel type, from CSO table TTM02 ("Mechanically Propelled Vehicles Under Licence"), filtered to the Private taxation class. EV share is the "Electric" fuel category's share of that total.
Top car brands and best-selling models
Each county's top-5 car brands come from CSO table TTM03 (the same "Under Licence" fleet-stock series as the fuel mix above, but broken down by vehicle make instead), filtered to the Private taxation class. Best-selling new car rankings come from TEM20 (make and model, national, since 2014) and, for fuel-specific rankings like best-selling electric cars, TEM28 (since January 2024). All three list individual makes/models plus a residual "All other makes" or "Other" bucket, which is excluded from the rankings shown.
Where the numbers come from
- CSO PxStat API (data.cso.ie), source tables sourced from the Department of Transport, licensed CC BY 4.0.
- Data last fetched: 21 October 2026.
Caveats
- DOTM08/TTM02 county dimension uses GUID codes assigned by the Department of Transport; FY001 (census) uses plain 2-digit codes. Joined by matching label text (see codelists.COUNTY_CROSSWALK) -- there is no CSO-published crosswalk table.
- 'Licensed for the first time' (TEM01/TEM12, a flow) and 'under licence' / fleet snapshot (TTM02/DOTM08, a stock) are different concepts -- don't subtract or compare them directly.
- DOTM08's CO2 bands are WLTP-era (post-2021); older vehicles in the live fleet are bucketed into these bands retroactively, not re-tested under WLTP, so 'average band' trends over a long period mix two emissions-testing regimes.
- All monthly CSO figures are explicitly marked provisional and subject to revision -- don't treat the latest 1-2 months as final.
- Per-capita figures use the 2022 census population as a fixed denominator (no annual county population series exists), so they drift low for fast-growing counties the further past 2022 the fleet data gets.
- TEM20 (new-car make/model, 2014+) and TEM28 (same, by fuel, 2024+) have different history lengths -- don't build a single trend chart spanning both without noting the join.
- TTM03's county dimension uses the same GUID scheme as DOTM08/TTM02; its 'All makes'/'All other makes' rows (codes '-'/'998') are excluded from fleet_by_county_make.json, so per-county make totals will not sum to that county's total fleet count -- 'All other makes' is a real, non-trivial chunk.
Corrections
If you think a figure is wrong, tell us.