What are the most fuel efficient small cars?

I've been doing some small car fuel efficiency comparisons. In other words which small cars give you the most in return for the fuel you put in them.

It's not just a matter of fuel economy. We put fuel in a car to make it go, so performance is a factor. We also have to consider CO2 emissions.

To calculate some measure of efficiency that's fair we need a clear standard.

Fuel economy has not improved much in the past. An average 1.2 small car had a combined 47 mpg 15 years ago and fuel consumption hadn't changed much 5 years ago. So let's say we want to see a combined figure of 57 mpg, today.

It's the same story with small car performance. The average small 1.2 car has had a maximum speed of about 90 mph for decades. So let's say we want to see 99 mph. We can't do over 70 anyway.

Car manufacturers have been focused on CO2 emissions. If you go back 5-years there were only about 10 small petrol engine cars with CO2 emission under 120 g/km. There were 24 diesel engine cars with emissions under 120 g/km which included the larger Fiat Punto and Renault Megane.

So, shall we set the standard for small car fuel efficiency at 57 mpg combined, 99 mph and emissions under 120? Which cars give us the most for the petrol we put in? Here are my results.

Small city cars with petrol engines nearly all have low emissions, do over 50 mpg and 90 mph. However, only the Hyundai i10 1.2 and Peugeot 107 qualify and meet my standard. Larger small cars just don't crack it. A lot come close. The Mini, Yaris and 1.0 Corsa almost qualify.

You have to look at diesel to have any choice. Almost every small car - tiny city car, super-mini or super-sized mini - has low fuel consumption, low CO2 emissions and some performance. Some diesels are quite quick.

Now let me put the dampers on this. A new diesel engine small car will likely cost more than a small car with a diesel engine. Let's say £1,000.00 more. The fuel cost advantage to diesel may only be £100 per 12,000 miles - a years motoring. So you could be waiting 10 years for your pay-back.

Which all means in my opinion, only the petrol engine Hyundai i10 1.2 and Peugeot 107, possibly the Mini, Yaris and 1.0 Corsa are contenders for the title most fuel efficient. However that's on my criteria and calculations. As I've said a lot come very close to the standards I set so it's worth looking at all of my charts over at A Guide on Small Car Economy, Emissions and Performance.

Note at the bottom of this page the VCA say you should not rank cars with similar figures. I guess you'll find more similarities than differences. So be careful about making decisions only on mpg because there may be no difference on the road. Versatility and safety are just two important features to consider and there you will find differences.

Regards
Ralph