Peugeot 308: Battle of the pumps

  • We pit our e-THP petrol against the BlueHDi diesel 308
  • Diesel offers greater efficiency and performance
  • How soon will it pay for itself though?

It’s difficult to pretend I was thrilled when I learned that my Peugeot 308 long-termer was going to be a petrol-powered example. After all, with my much-mentioned 74 miles each-way commute, a frugal diesel would make much more sense, especially given that the all-new 2.0-litre BlueHDi motor is one of the most frugal available.

When we recently had a near enough identical specification 308 powered by the 148bhp edition of the new powerplant in for testing, the opportunity to drive it and Parkers’ 128bhp e-THP example back to back was too good to miss.

So, was it a one-horse race? Well, no – far from it.

There’s no escaping the fact that the diesel 308 whips the petrol version into shape when it comes to fuel efficiency and CO2 emissions. Posting figures of 70.6mpg and 105g/km, the BlueHDi is ahead of the e-THP at a claimed 58.9mpg and 110g/km.

It’s not quite that clear cut though: in reality our petrol 308 is averaging a still-decent 40.8mpg, whereas that particular diesel is more likely to get a real-world figure of around 52mpg. And despite the difference in CO2 figures, both fall into VED car tax band B – costing just £20 per year.

In BlueHDi 150 form the 308’s a more powerful steed too; as well as a higher top speed, the sprint from standstill to 62mph is shaved by 1.5 seconds to 8.9, helped not only by 20bhp extra, but a meatier 140Nm of additional torque at 370Nm.

So, what’s stopping the diesel being the better car purely through those figures? On paper it’s superior to the e-THP 130 and on the road there’s a greater urgency and efficiency in the way it goes about its business, too.

Subjectively, some will simply prefer the noise of the petrol engine. Sure, as a three-cylinder unit, there’s more of a raspy thrum than most people will have become accustomed to in their four-pot hatchbacks, but the noise isn’t, to my ears, offensive. Although the diesel’s a refined unit, there’s still an agricultural clatter audible on start-ups and under harder acceleration.

More pertinent is the cost, and more specifically, how far you’d have to travel in order to recoup the additional outlay of the diesel.

Without extra-cost options, the Blue HDi 150 is £2,050 more expensive than the e-THP 130 in top-of-the-range Feline trim. Using those official fuel consumption claims at today’s average pump prices for diesel and unleaded, if you covered 12,000 miles per year you’d only spend £167 more on petrol.

Okay, so the official efficiency claims are misleading: how does our petrol 308’s current average of 40.8mpg compare to the indicated 52mpg the BlueHDi offered on test? That same 12,000 miles over 12 months would cost just £332 extra at the green pump.

In other words, not taking into account the diesel’s better resale value and assuming fuel prices and other taxation remained constant, you’d need to travel just over 74,000 miles further in the diesel 308 before the difference is purchase price was negated. Based on the official fuel consumption claims it’s an enormous 147,000 miles further.

With Boris Johnson making noises about levying higher taxation rates on diesels, and other cities looking at congestion charging too, it may mean that petrol makes even more sense than ever.

What can we draw from this? Firstly that in many instances, most people would still be better off buying a petrol car over a diesel. My average mileage is now 35,000 per annum – equating to £488 extra on petrol than diesel. I’d be looking at over four years of ownership to make the BlueHDi pay had I bought the 308 myself.

Before you sign on the dotted line, do the maths with the Parkers Cost of Ownership tool – you, like me, might be better off with a petrol after all.

Total mileage: 3,404 miles (started at 1,256) Average mpg: 40.8 mpg