Car emissions have significant implications for public health in terms of local air pollution but also in terms of greenhouse gas emissions (a major threat to international health). Car fuel efficiency also has implications for domestic living costs and energy security at a national level. Here we add new data to previous work in 2005 to describe recent trends in the New Zealand setting.Methods—We obtained a list of the top 10 selling new car models in 2011 for New Zealand (personal communication with Perry Kerr, Chief Executive Officer of the Motor Industry Association, 2012) and for the United Kingdom.1 Data on fuel efficiency, greenhouse ratings and pollution ratings were obtained from the same official Australian Government website (Green Vehicle Guide:http://www.greenvehicleguide.gov.au/GVGPublicUI/home.aspx) used in a previous study2in which one of us (NW) was involved. To maximise comparability with the previous study, we decided against using a similar website that has since become available for the New Zealand setting (http://rightcar.govt.nz). Neither database differentiates between model variants (e.g., the Holden Commodore is available in 3.0L and 6.0L engine size variants), so the variant with the median fuel economy was used in the analysis. Three of the top 10 selling models in the United Kingdom were missing from the Australian database, and were omitted from the analysis.Results & Discussion—The top 10 selling new car models for New Zealand between the years 2005 and 2011 improved from a health perspective with respect to: (i) greenhouse ratings (based on CO2 emissions), from 5.4/10 to 6.2/10; (ii) air pollution ratings, from 5.6/10 to 6.8/10; and (iii) fuel efficiency, from 10.0L/100km to 8.5L/100km. Mean engine size decreased from 2.80L to 2.49L (see Table 1).These trends may be partly explained by impacts of the global economic crisis in New Zealand along with higher fuel prices (with the petrol price increasing in New Zealand from ~$1.50/L in 2005 to $2.06/L in December 2011). Other contributing factors may be: (i) increased awareness by car buyers of issues around climate change and air pollution; (ii) changing demographics with smaller families and households (favouring smaller cars); (iii) growing parking constraints in cities (possibly favouring smaller cars); and (iv) and fashions relating to car size.But despite these improvements, the top 10 selling new car models in 2011 for New Zealand were somewhat behind (in efficiency and pollution rankings) compared to the equivalent models for the United Kingdom (see Table 1). Similarly, when compared to the winner of the "2010 AA Energywise Rally" held in New Zealand (see:http://uat.aa.co.nz/about/events/AAenergywiserally/Pages/default.aspx). To accelerate progress towards low pollution levels and fuel efficiency, the New Zealand Government could consider following the lead of other countries to have tighter fuel efficiency standards for vehicles and to adopt standards on CO2 emission levels (such as those forthcoming in the European Union3 and the United States4). Higher registration fees or taxes on inefficient vehicles with larger engines are another approach. Table 1. Mean performance and pollution ratings of the top selling cars in New Zealand and comparisons over time and with selected other cars Car performance features* Advertised cars (NZ magazines 2001-2005)2 Top 10 selling cars in NZ in 20052 Top 10 selling cars in NZ in 2011 Top selling cars in UK in 2011† AA Energywise Rally Winner (2010) Mean CO2 produced (per km travelled) - - 202.4 156.7 109.0 Mean "Greenhouse ratings" (score of 10 is "best") 5.3/10 5.4/10 6.2/10 7.4/10 8.5/10 Mean "Air pollution ratings" (score of 10 is "best") 5.4/10 5.6/10 6.8/10 7.1/10 8.5/10 Mean engine size (L) 2.98 2.80 2.49 1.73 1.30 Mean fuel efficiency‡ (L/100 km) 9.8 10.0 8.5 6.7 4.6 Notes: See the full dataset at: http://www.scribd.com/doc/79802639/Car-Efficiency-Data-for-NZ-and-UK-2011 * Ratings were based on those in an Australian Government website "the Green Vehicle Guide" (http://www.greenvehicleguide.gov.au/GVGPublicUI/home.aspx). † Three of the top 10 selling models in the United Kingdom were missing from the Australian database, and were omitted from the analysis present here. ‡ Using the "combined" consumption of urban and extra-urban driving (see calculation details at: http://www.fuelsaver.govt.nz/explain.html). Vimal Patel,* Nick Wilson Department of Public Health, University of Otago, Wellington *Correspondence: vimal.patel@otago.ac.nz

Car emissions have significant implications for public health in terms of local air pollution but also in terms of greenhouse gas emissions (a major threat to international health). Car fuel efficiency also has implications for domestic living costs and energy security at a national level. Here we add new data to previous work in 2005 to describe recent trends in the New Zealand setting.Methods—We obtained a list of the top 10 selling new car models in 2011 for New Zealand (personal communication with Perry Kerr, Chief Executive Officer of the Motor Industry Association, 2012) and for the United Kingdom.1 Data on fuel efficiency, greenhouse ratings and pollution ratings were obtained from the same official Australian Government website (Green Vehicle Guide:http://www.greenvehicleguide.gov.au/GVGPublicUI/home.aspx) used in a previous study2in which one of us (NW) was involved. To maximise comparability with the previous study, we decided against using a similar website that has since become available for the New Zealand setting (http://rightcar.govt.nz). Neither database differentiates between model variants (e.g., the Holden Commodore is available in 3.0L and 6.0L engine size variants), so the variant with the median fuel economy was used in the analysis. Three of the top 10 selling models in the United Kingdom were missing from the Australian database, and were omitted from the analysis.Results & Discussion—The top 10 selling new car models for New Zealand between the years 2005 and 2011 improved from a health perspective with respect to: (i) greenhouse ratings (based on CO2 emissions), from 5.4/10 to 6.2/10; (ii) air pollution ratings, from 5.6/10 to 6.8/10; and (iii) fuel efficiency, from 10.0L/100km to 8.5L/100km. Mean engine size decreased from 2.80L to 2.49L (see Table 1).These trends may be partly explained by impacts of the global economic crisis in New Zealand along with higher fuel prices (with the petrol price increasing in New Zealand from ~$1.50/L in 2005 to $2.06/L in December 2011). Other contributing factors may be: (i) increased awareness by car buyers of issues around climate change and air pollution; (ii) changing demographics with smaller families and households (favouring smaller cars); (iii) growing parking constraints in cities (possibly favouring smaller cars); and (iv) and fashions relating to car size.But despite these improvements, the top 10 selling new car models in 2011 for New Zealand were somewhat behind (in efficiency and pollution rankings) compared to the equivalent models for the United Kingdom (see Table 1). Similarly, when compared to the winner of the "2010 AA Energywise Rally" held in New Zealand (see:http://uat.aa.co.nz/about/events/AAenergywiserally/Pages/default.aspx). To accelerate progress towards low pollution levels and fuel efficiency, the New Zealand Government could consider following the lead of other countries to have tighter fuel efficiency standards for vehicles and to adopt standards on CO2 emission levels (such as those forthcoming in the European Union3 and the United States4). Higher registration fees or taxes on inefficient vehicles with larger engines are another approach. Table 1. Mean performance and pollution ratings of the top selling cars in New Zealand and comparisons over time and with selected other cars Car performance features* Advertised cars (NZ magazines 2001-2005)2 Top 10 selling cars in NZ in 20052 Top 10 selling cars in NZ in 2011 Top selling cars in UK in 2011† AA Energywise Rally Winner (2010) Mean CO2 produced (per km travelled) - - 202.4 156.7 109.0 Mean "Greenhouse ratings" (score of 10 is "best") 5.3/10 5.4/10 6.2/10 7.4/10 8.5/10 Mean "Air pollution ratings" (score of 10 is "best") 5.4/10 5.6/10 6.8/10 7.1/10 8.5/10 Mean engine size (L) 2.98 2.80 2.49 1.73 1.30 Mean fuel efficiency‡ (L/100 km) 9.8 10.0 8.5 6.7 4.6 Notes: See the full dataset at: http://www.scribd.com/doc/79802639/Car-Efficiency-Data-for-NZ-and-UK-2011 * Ratings were based on those in an Australian Government website "the Green Vehicle Guide" (http://www.greenvehicleguide.gov.au/GVGPublicUI/home.aspx). † Three of the top 10 selling models in the United Kingdom were missing from the Australian database, and were omitted from the analysis present here. ‡ Using the "combined" consumption of urban and extra-urban driving (see calculation details at: http://www.fuelsaver.govt.nz/explain.html). Vimal Patel,* Nick Wilson Department of Public Health, University of Otago, Wellington *Correspondence: vimal.patel@otago.ac.nz