I found this write-up on the Top-Gear website, may be of interest to a few of you. ::--
Sometimes car makers get caught sitting on their thumbs. Did VW and Ford mean to be so many years late with their midi-MPVs? And why haven't the Italians (with apologies to Lamborghini) come up with a chunky 4x4?
You could ask similar of Honda; why the delay in launching a diesel Accord? While just about everyone was producing Mondeo-sized diesels, the Accord has had to compete in the UK solely with petrol. So, excellent those Accord engines may be, but in a market segment where diesel now out-sells petrol, Honda has been forced to come up with d-power for its award-winning saloon.
Senior Chief Engineer Kenichi Nagahiro, previously responsible for Honda's winning Indycar engine programme, and also the man credited with inventing VTEC was assigned to head up this diesel project. But by Mr Nagahiro's own admission, initially this wasn't a job he wanted due to the un-glamorous disposition of the 'd' word. But with the brief to make the diesel behave as much like a petrol engine as possible, he and his team got stuck in and have succeeded with flying colours.
Firstly, I'd defy any Accord i-CTDi passenger not already 'primed' to even notice that this was a diesel engine. If you listen very carefully at start-up and at very low rpm you might just hear a split-second's worth of telltale d-noise, but otherwise not. And, from inside the cabin especially, although this lump doesn't sound exactly like a petrol engine, it doesn't sound like a diesel either; so even if pushed, I reckon most folk would guess it was a petrol. And at speed, even way above 100mph, which I might add is a complete doddle, this Accord remains so smooth, quiet and unobtrusive that you'd just assume it was petrol-powered, and possibly a six-cylinder one at that.
Of course, any semi-alert driver would notice something was up because there's such usable, accessible power at ridiculously low rpm. Honda claims 138bhp at 4,000rpm but, more importantly, torque of 251lb ft at 2,000rpm. Now, let's see, that's a bit less bhp than the class-leading Mercedes 220CDi and Renault 2.2 dCi units (both 150bhp), but the Honda equals the Merc and betters the Renault on torque, while at the same time running on a meagre - for a diesel - 16.7:1 compression ratio. And why the low cr? Because a higher ratio, while being good for peak power, is detrimental to quietness and smoothness.
Out on the road there's no discernible powerband - no thump in the back at a particular engine speed, just a strong, clean power delivery from just over tickover to the 4,500rpm red line. Additionally, this engine already complies with the extremely stringent Euro 4 emissions regs for 2005 without the use of a particulate filter, (currently under development). And in case that doesn't impress you, then it also means you could be paying less in company car tax. As for mpg, how does 52.3 on the combined cycle grab you?
In short, this engine was worth the wait. But now I'm thinking; unless Type-R style performance is your priority, just what are the advantages of a petrol engine?
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