Real MPG and real emissions

Some friends are looking to change car soon. They are obsessed with emissions issues and look for low MPG cars with low carbon. Their current car (Smart) does not come remotely close to its real MPG. Its predecessor (Skoda Fabia 1.9 TDI) always did as claimed.

To obtain real emissions, would a reasonable proxy be to uplift the carbon value by claimed MPG over Real MPG? If so their Smart is only marginally better on emissions than their old Fabia which achieves 101% of its claimed MPG figure.

Asked on 9 October 2016 by Busmanuk

Answered by Honest John
Absolutely. If a car gets half the NEDC combined fuel economy it is by definition using twice as much fuel and emitting twice as much CO2.
Similar questions
My Ford Mondeo the dashboard info tells me my average mpg is 57.2 - way above what I see on Real MPG. Could this be a true figure or computer error?
My Ford Focus 1.0 EcoBoost is not doing the miles per gallon it should. I'm only getting 40mpg to 45mpg. Why is this?
I'm looking for a new company car and l'm interested in hybrid vehicles due to the lower BiK rates in comparison with diesels. I will be doing regular 100-mile journeys, so need to factor in real world...
 

Ask Honest John

Value my car

Save £75 on Warranty using code HJ75

with MotorEasy

Get a warranty quote

Save 10% on GAP Insurance

Use HJ10 to save on an ALA policy

See offer