Kev - we've debated this ad-nauseum. My V6 75 was smooth and quiet at 6500 rpm, which it was driven at for long periods of time. My current 5 cyl Volvo is also smooth. Grunt in diesels comes not from the fuel or the combustion process per se but from the turbocharging - a process that can be applied to petrol engines too. Without it there would be the same linear increase in power that there is in a naturally aspirated petrol engine, with the downside being that the inability to acheive high RPM means little power.
My 150bhp, non turbo Rover was a different animal to my mates 150bhp PD golf, which alwaysfeltfaster but wasn't really, especially if you caught it off boost. Of course the turbo Volvo is a different matter...
My car develops 90% peak torque from 1800 rpm to 6000 rpm, a 3:1 ratio. Most diesels will be from 2000 to 4000 rpm, meaningmoregear changes to make similar progress - I can hold 3rd gear from 20mph to 90mph and get good accelleration without changing gear, or 2nd from 10mph to 60mph. A diesel would need to change gear once or twice to get the same effect.
I drove the D5 Volvo, a cracking car with ultimately the same pace, but not as easy to drive quickly as it was so jeckyll and hyde with the high amount of boost required to get the power. Same with the BMW 530 I drove. Both would have been better with auto boxes, but that hurts the diesels USP, economy.
A new oneI followed a police a car for several miles along a SC A road until we reached a roundabout. He went all the way round and came along behind me. We...
Ultimately the choice comes down to that - economy. The Astra Eco4 I was driving a couple of weeks ago was hateful in every way, apart from it's 60+mpg real world economy. The S80 D5 I drove got 40mpg with a heavy right foot. My 2.0T has more power than the D5, costs 2000 quid less, does 30mpg. So for 2000 quid more I could have saved 80 gallons every 10000 miles and missed out on 17 bhp and a wider power band.
Diesels make sense for high load high mileage vehicles or for people for whom the economy will pay off, but the tradeoff is lower performance.
