[WeaverBeaver]

It seems pretty much every car I've ever owned that has been turbocharged, petrol or diesel, the real life peak torque point in the rev range has always been way higher than what the manufacturer claims.

My old Merc c350 cdi was a prime example - quoted max torque at 1600rpm, but in reality the turbo was asleep below 2.5-3k. Old Audi TTS the same. Even the mighty 335d quotes peak torque starting at 1500rpm but it always felt more like 2k was when it started to build with peak around 3k.

Is it just me or like quoted mpg claims, are manufacturers having a bit of a joke?

[robbiep]

Torque doesn't 'peak' like BHP. In diesels particularly, it climbs, reaches the top, (often at 1.5-2k rpm) and then usually sits there for a considerable part of the rev range, starting to drop after 4k rpm. The BHP is, at the same time, climbing through the range, so it the overall effect is that you feel the most 'shove' happens somewhere around 3-3.5k rpm, when the torque hasn't started to drop away, but the BHP is reaching it's max.

Have a look at some of the chipped car graphs, they explain it far better than I can.

[NISFAN]

The figures the manufacturers use are from an engine dyno, which is completely different to a chassis dyno or butt dyno. An engine dyno is able to hold the revs by varying the load. When you do that, the boost pressure is able to build to a high value and stabilise, giving good torque readings.
When you boot it, it takes some time for the turbo to produce maximum boost.....lag.