Smouldering ruins: PH Blog

Why the end of the diesel dream might be the best thing that's happened to the car industry in decades

Amazing to think just last week it was business as usual at the Frankfurt show; Winterkorn was enjoying his first VW Group night without deference to Dr Piech, local manufacturers were riding high and the German grip on European car manufacturing was as firm as ever.

And now look.

When making cars for regs goes really wrong!

But who's to blame for this whole thing - car makers like VW or the legislators whose rules they were bending? Attempts by governments to force manufacturers into making cleaner engines have a proven record of unintended consequences. Take America's Clean Air Act of the 70s and the strangling effect of smog filtration that saw huge V8s wheezing out barely more than 100hp while guzzling huge amounts of fuel.

Same as today. Well-intentioned rules to try and reduce the harmful emissions actually end up being counter-productive. The generous view is the car makers simply create engines to the letter of the law, meaning our cars are currently built to achieve lab tested CO2 and mpg figures with actual real-world performance a secondary concern. It's not quite as bad as the smog strangled Yank tanks of the 70s but the over-geared, rev-strangled, over-boosted engines we're now stuck with are built with these targets in mind, not drivers. VW was simply employing ruthless logic by engineering its diesel motors to pass the tests off the road while delivering the performance customers demanded on it.

What will the VW scandal do for diesel?

At the same time the fixation with CO2 means we as drivers can kid ourselves a two-tonne luxury SUV with a big diesel engine is as virtuous as a family hatchback because the bottom line g/km figure is the same. Or, in performance terms, a BMW M3 can go from 263g/km to 194g/km in a generation without any compromise in performance and claim itself a tree hugger as well as a tyre shredder. This is nonsense.

Actual mpg on the road isn't improved by the same proportion and the engines haven't suddenly got that more efficient. They have got more complicated and better at hitting the targets set down by legislators. But that's not quite the same thing. The C63 S I was driving last week has CO2 of 192g/km and official mpg of 34.4mpg compared with 285g/km and 23.1mpg of my old 6.2-litre 507 long termer. But according to the trip in comparable driving I was getting maybe two or three mpg more. On paper the new engine is 'better' but for the sake of a few mpg I'd be happy with the old 6.2 V8, ta.

Efficient and interesting can happen!

There are exceptions, notably when the engineers take the lead and attempt to actually solve a problem rather than just achieve the required numbers by the simplest method possible. As in 70s California when Honda took a different approach with its lean-burn CVCC-engined Civic, the idea being to burn the fuel more efficiently rather than just chuck it through a big engine and let the smog gear mop up the mess.

See also Mazda today with its Skyactiv engines. Both units go against the accepted grain by keeping generous cubic capacity, the petrol sticking with normal aspiration and a high compression ratio while the diesel is lower than usual permitting a lighter engine and increasing refinement. Combine the former with lightweight engineering and you've got a new MX-5 weighing just 50kg or so more than its equivalent of 25 years ago but with all the advances in safety made in that time.

Proving what? If you tell the engineers to build engines that hit emissions targets they'll do it, by fair means or foul. But if they're given free rein to use their skill and actually make engines more efficient the results are often more creative, interesting and effective. Make better use of a given amount of fuel and we're all winners, whether we're out to go faster or just pump less nasty stuff out in our wake.

Here's a plan then. Let's leave the engine building to the engineers, eh?

Dan

[Sources: Honda]

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