Do technical improvements lead to real efficiency gains? Disaggregating changes in transport energy intensity

Abstract

Fuel economy standards are a key measure to increase the rate of efficiency improvements in passenger cars. The fuel consumption of vehicles can be improved in three ways: incremental technical efficiency improvements within powertrain technologies, market shifts to more efficient types of powertrains and by limiting increases in the size and performance of vehicles. This study quantifies the effect of each of these three drivers on the fuel consumption of British vehicles between 2001 and 2018 using driver-reported data on real-world fuel consumption. Analysis shows the introduction of EU fuel economy standards in 2008/09 had little effect on the rate of real technical efficiency improvements in British vehicles. Instead of adopting technical improvements at a higher rate or limiting the size and power of vehicles, these results suggest vehicle manufacturers met emissions standards by increasing the divergence between laboratory tests and real-world fuel consumption. This study adds to the growing literature calling for official test procedures to be representative of real-world driving.

Modelling transport emissions in an uncertain future: What actions make a difference?

“…The real-world fuel efficiency of vehicles from model years 2001-2018 is sourced from past work by the authors (Craglia and Cullen, 2019). These are linearly extrapolated backwards to 1994 in order to attain the fuel efficiency of all vehicles in use in the base year 2018.…”

A new method to estimate the lifetime of long‐life product categories

“…Using bottom‐up data, the magnitude of steel flows into and out of the UK vehicle stock were estimated for each year given that the following quantities were known: the number of new and scrapped vehicles (UK Department for Transport, 2019a, 2019c, 2019b), the average mass of new vehicles (Craglia & Cullen, 2019; McGregor, 2017) and the average steel content of new vehicles (Serrenho, Norman, & Allwood, 2017). In general, estimates of the steel scrap output from the vehicle stock is not publicly available and requires creating a stock model to estimate the age distribution of vehicles on the road.…”

Do vehicle efficiency improvements lead to energy savings? The rebound effect in Great Britain

“…A previous paper by the authors [40] built a dataset of vehicles sold between 2001 and 2018 using a combination of publicly available data sources [41][42][43]. Using this data, we attribute a size segment (e.g.…”

“…The dataset created in [40] sourced driver reported, realworld fuel consumption records for new British vehicles sold between 2001 and 2018 and was able to determine a sales-weighted estimate of new car, real-world fuel consumption for the first time. This showed that the difference between manufacturer reported (type-approval) fuel consumption and driver reported (real-world) fuel consumption has been increasing over time.…”

“…Failure to account for this fact could bias investigations into the rebound effects of different types of vehicle. For vehicles registered after the year 2000, we attempt to match a 'real-world' fuel consumption estimate using fuzzy matching algorithms (see [40]) by vehicle manufacturer, model, engine size, fuel type and year of first registration. Since no data on transmission type (Manual/Auto) or drivetrain (AWD) are available in the MOT data, the sales-weighted average data for each group of matched vehicles is used.…”