From: NM on
Conor wrote:
> In article <>, Steve Firth
> says...
>> I've checked it against GPS and do so fairly regularly. At an indicated
>> 75mph the true speed is about 68-69mph. Fairly typical for a Ford.
> At 70MPH, you're screaming the nuts off a HGV engine.
Rubbish, if the DAF I usually drive was not speed limited it would
cruise at about 85mph with the rev counter on the upper edge of the
green sector, if you want to take it into the end of the yellow it would
be doing nearly 100mph. It's deliberatly geared to do 56mph just into
the green (economical sector).

I wouldn't like to be the one paying the fuel bills though.
From: Niall Wallace on
"Knight Of The Road" <russiatrucking(a)> wrote in message
> I don't know what speed they were doing, I wasn't there.
> If my car speedo was registering 75 mph I would be extremely surprised if
> even one, let alone three HGVs could overtake me on a level road.
> Have you thought about getting your speedometer calibrated?

It is, 10% over reading is allowed while 0% isn't. If you produced a
standard speedo and set it to be 100% accurate for the standard 15" steel
wheel model it would be under reading for the 17" wheeled sports model with
that slightly larger tyre circumference. Or even if the car owner chose a
different profile tyre for their 15" steelies.

My current car which is suffering from rear end tin worm and may not have
another meeting with the MOT man has the speedo calibrated for wide alloys
(4.5) and 185/65/15 tyres. It takes a few more revs to get to 70 on the
motorway than when it was on narrower Alloys and the same tyres, and I
reckon it knocked around 5mph off the speed at 5500rpm in 4th.