With the current anti-diesel atmosphere, it’s too easy to get carried away with some of the claimed fuel economy figures for many of the latest turbocharged petrol cars and forget that you won’t, in reality, achieve anywhere near those on-paper figures. In fact, you may well get less than you might even reasonably expect, because many of these ìofficialî figures for petrol cars are even more over-optimistic than the equivalent figures usually are for diesels. You shouldn’t, for example, reasonably expect to achieve anywhere near the claimed 57mpg combined figure for a certain popular French SUV with a 1.2-litre 128bhp turbocharged petrol engine but, on the other hand, you might hope for rather more than the miserable 37mpg average fuel economy reported by real life owners. It’s nowhere near the 51mpg that drivers of the 118bhp 1.6 turbodiesel version of the same model are reporting that they are getting ñ and, with diesel and petrol costing near enough the same just now, it means that the petrol variant costs you well over a third more in fuel bills than the diesel.
This isn’t the place for naming names, and there are no real significant differences between manufacturers for us to highlight, but here are some more examples of the same petrol versus diesel fuel economy situation, with the typical figures that you can expect to get from some petrol powered alternatives to popular diesel cars:
| Genre | Petrol engine | Real-world mpg | Diesel engine | Real-world mpg |
| Popular European hatchback | 1.0 Turbo Petrol | 43mpg | 1.5 Turbo Diesel | 56mpg |
| Popular European hatchback | 1.6 Turbo Petrol | 35mpg | 2.0 Turbo Diesel | 51mpg |
| Acclaimed executive saloon | 2.0 Turbo Petrol | 36mpg | 2.0 Turbo Diesel | 51mpg |
| European seven-seat MPV | 1.4 Turbo Petrol | 34mpg | 2.0 Turbo Diesel | 53mpg |
| Quality German saloon | 2.0 Turbo Petrol | 33mpg | 2.0 Turbo Diesel | 57mpg |
| Popular German hatchback | 1.5 Turbo Petrol | 36mpg | 1.5 Turbo Diesel | 51mpg |
| Stylish UK built hatchback | 1.5 Turbo Petrol | 43mpg | 1.5 Turbo Diesel | 51mpg |
| Stylish UK built hatchback | 2.0 Turbo Petrol | 41mpg | 2.0 Turbo Diesel | 50mpg |
| Top-selling Japanese SUV | 1.2 Turbo Petrol | 37mpg | 1.5 Turbo Diesel | 53mpg |
| Top-selling Japanese SUV | 1.6 Turbo Petrol | 40mpg | 1.6 Turbo Diesel | 53mpg |
| Popular German hatchback | 1.4 Turbo Petrol | 45mpg | 2.0 Turbo Diesel | 54mpg |
You’ll see that there’s quite some variation of the mpg penalty for switching from diesel to petrol power, but the average difference works out at around a 15mpg loss, or 38mpg versus 53mpg, with just under 40 per cent more fuel used by the petrol powered cars, according to these average figures registered by owners on the www.honestjohn.co.uk/realmpg/ website, whom we thank for these figures. Over a 10,000 mile year, that means, with fuel at £5.50 a gallon, you’ll need to buy another 64 gallons of fuel a year, at a cost of around £350, to fuel up your petrol car; plus, and this is the real killer point, the typical one-off cost of, at the very least, £1,500 to £2,000 to change cars, if you’re daft enough to take fright at the recent anti-diesel scares, and switch over to petrol power.
If you’ve an older diesel (pre Euro-5), then it might be a smart thing to wait a while and then pick up a nice low mileage used Euro-5 or Euro-6 car (both of which may well escape any of the anti-diesel exclusions, penalties and charges) at a good price later this year, when we’ll know precisely what grants and penalties may be coming into operation. But the costs of switching from diesel to petrol are far, far greater than most people are likely to ever encounter in any diesel emissions charging scenario, unless they regularly commute into central London and city centres, and now is not the time to trade in a good Euro-5 or Euro-6 diesel car in the panic that, sadly, seems to have been generated by the recent media diesel-bashing.
Victor Harman
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One Response
As a city dweller with lungs and likes to breathe, I would rather have a 35mpg petrol car which complies with Euro 6 Nox emissions than a 56 mpg diesel car if the latter has the typical factor of 5 non-compliance for Nox emissions