This was on Skoda UK. Thought it might be of interest, if not already spotted.

P.

METROPOLITAN-POLICE-SERVICE-REPORTS2.pdf

Very interesting! I fancied a 1.8 tsi but after reading that report I would say that the vRS diesel is the daddy?

The 312mm brake set up on the VRS is IMHO much better than the 288 setup

Now that's what you call a test drive!!!

Those guys could clearly get jobs mini-cabbing

once they've left the police!

The 0-60 time of 12.86 seconds for the fabia 1.9tdi was completely inaccurate! This vehicle can do the 0-60 sprint in under 10.5 seconds if driven correctly. They obviously do not know how to drive diesels and must have driven it like a petrol or they drive their cars like grannies!! :confused:

Mark

The 0-60 time of 12.86 seconds for the fabia 1.9tdi was completely inaccurate! This vehicle can do the 0-60 sprint in under 10.5 seconds if driven correctly. They obviously do not know how to drive diesels and must have driven it like a petrol or they drive their cars like grannies!! :confused:

Mark

Some cars come from the production line better than others due to tollerances in the machines that make certain parts of the engine and drivetrain.

The one they drove may of been a bad un, yours may be a good un.

Steve

Totally valid point Steve, it is very true there are differences between the same engines, due to the reasons you stated. Though, you must admit that it is quite a large difference, i.e. more than two seconds! Not only that but most pd105 vw engines do generally read between 100bhp and 115bhp on a rolling road and therefore all 0-60s should be at least below 11.5 seconds!

It is the case that many people do drive diesels poorly, as you will no doubt know, you should change gear while still in the torque band to maximise acceleration. It is conceivable that the police testers are unaware of this!!!

The 0-60 time of 12.86 seconds for the fabia 1.9tdi was completely inaccurate! This vehicle can do the 0-60 sprint in under 10.5 seconds if driven correctly. They obviously do not know how to drive diesels and must have driven it like a petrol or they drive their cars like grannies!! :confused:

Mark

And the Police Test report is with 2 fully equipped Police Officers with a load of at least 80 - 100Kg in the boot to simulate the extra police equipment Plus the drag associated with roof bars etc so an increase of 2 seconds is perfectly reasonable.

ALSO

The vehicles will not have been "red lined" in the 0 - 60

They obviously do not know how to drive diesels and must have driven it like a petrol or they drive their cars like grannies!! :confused:

If you believe that, then I would suggest getting a ride with a police driver

Chris

It is the case that many people do drive diesels poorly, as you will no doubt know, you should change gear while still in the torque band to maximise acceleration.

It is the case most people drive diesels poorly, mainly down to the fact they change gear too *early* and lose momentum and acceleration. 4k rpm or slightly above is an optimum change point in all of the VAG diesels I've driven to maximise acceleration...

Chris

I disagree about the 4k thing Chris.

The old 110 was before that as is the 1.4tdi.

You can happily go there in a PD140/PD170 but I can't say i really feel the need.

Ah I missed out the word "modern" from my post. The 1.4 TDI I drove pulled nicely to 4k rpm.

Whether *you* feel the need is largely irrelevant If you want to maximise acceleration you need to use the full power band

Chris

To maximise the acc in a pump duse unit diesel it is best to change gear within the torque band, aiming to start at the base of the torque band in the next up shift. Therefore there is no need to rev above 3500 when trying to accelerate rapidly!!

To maximise the acc in a pump duse unit diesel it is best to change gear within the torque band, aiming to start at the base of the torque band in the next up shift. Therefore there is no need to rev above 3500 when trying to accelerate rapidly!!

What is this based on?

Chris

Because the torque comes early in a diesel engine, the pulling power significantly reduces after about 3500rpm meaning that the power gained from there on is less efficient than the power that could be available in the next gear, at the beginning of the torque band. This of course does not mean speed will not increase in the latter revs, it will of course, but it will not get there as quickly as if one had changed gear a bit earlier. Saying this though it is important to hit 4.5k rpm on a regular basis through the gears as this helps to free up the engine and clean out the injector assembly promoting a more efficient engine. Just my thoughts though!

It is fair to say that that report makes the decision of my force to change from Mk1 vRS Estates to 2.0FSI 4x4 to 2.0TDI 4x4 quite strange. But hey, who am I to comment, I just work in them every day... I'm sure an engineer is far better placed to say what operational police officers need than an operational police officer...

Because the torque comes early in a diesel engine, the pulling power significantly reduces after about 3500rpm meaning that the power gained from there on is less efficient than the power that could be available in the next gear, at the beginning of the torque band. This of course does not mean speed will not increase in the latter revs, it will of course, but it will not get there as quickly as if one had changed gear a bit earlier. Saying this though it is important to hit 4.5k rpm on a regular basis through the gears as this helps to free up the engine and clean out the injector assembly promoting a more efficient engine. Just my thoughts though!

Ah, I see what you're saying. However, it's the torque at the wheels which matters which is the flywheel torque combined with the gear (torque multiplier). The lower the gear, the higher the multiplier so holding a low gear up until peak power will generally produce more torque at the wheels than changing up early.

This thread probably explains it better, but the torque curves seem to have been removed:

http://briskoda.net/forums/fabia/fabia-vrs-best-technique-max-performance/29215/

This plot is also interesting...

http://www.superchips.co.uk/curves/vagpd130.pdf

Chris

Ah, I see what you're saying. However, it's the torque at the wheels which matters which is the flywheel torque combined with the gear (torque multiplier). The lower the gear, the higher the multiplier so holding a low gear up until peak power will generally produce more torque at the wheels than changing up early.

This thread probably explains it better, but the torque curves seem to have been removed:

http://briskoda.net/forums/fabia/fabia-vrs-best-technique-max-performance/29215/

This plot is also interesting...

http://www.superchips.co.uk/curves/vagpd130.pdf

Chris

I have actually noticed this in real life in the fiat...

situation A-road overtaking... my RR graph shows I have over 150bhp between 2.5k and 4.5k, so in my mind, this should mean the overtake can be done in 3rd OR 4th, as its in that constant high power band in either gear , at typical a road overtake speeds....

HOWEVER, there is deffinatly more acceleration to be had when using 3rd, and revving to 4.5k, than there is in using 4th (even though its still in the high power band in 4th) and its all down to the gearing, and what is actually being given at the wheels, rather than at the flywheel......

I wonder if it is possible to find the complete 'library' of test reports for all cars evaluated by the police?

If you believe that, then I would suggest getting a ride with a police driver

Chris

Yep very true, I was walking home very late at night it was cold and icey, a copper pulled up next to me, I thought he we go ( I had a run in with the police abit before got slammed in a cell, they thought i was part of a gang, even though the gang was outside the club and i was in it, not impressed, I got a cut head and a bruised leg a repeatly punched by a bouncer top night out, anyways that was before ) So this copper pulls up and ask are you known to the police, I said well yeah kind of now, I told him where I lived about 5 miles away at the time, they said Jump in the back then we aint all bad coppers you know, that drive home was the best bit of driving I have ever been in, blimey the roads where dead cos it was late, he ran reds flew past speed cameras, I asked what about them, he said no worrys lights are on we are reacting to emergency, he took a roundabout like you wouldnt believe, sweeping bends well under control, and this was a icey night since then I have a new found faith in the guys, its still them and me though, but those two coppers who ever you were HATS OF TO YOU

so we are paying police to test cars which have already been tested and met loads of standards to be able to be used on the roads?

Also 0-60 times etc are also available from any car magazine.

What i'm saying is this testing to some degree may be a waste of tax payers money!!!!

Go on disagree with me........ lets have a depate!!!

:eek::eek::eek:

They're testing if they are fit for a police purpose though, which is different to the manufacturer's testing. For example, just because a car is capable of 130mph, doesn't mean that it will be able to drive at that speed for a sustained period of time, or that the brakes are capable of 20 stops from that speed on a blue light run, etc. I also suspect that not all manufacturers are completely honest when they test....

Sounds like quite good work if you can get it, although it seems that you do get to test some pretty naff/uninspiring cars too....

Chris

so we are paying police to test cars which have already been tested and met loads of standards to be able to be used on the roads?

Also 0-60 times etc are also available from any car magazine.

What i'm saying is this testing to some degree may be a waste of tax payers money!!!!

Go on disagree with me........ lets have a depate!!!

:eek::eek::eek:

They're being tested to see if they are up to being in use for 24 hours a day, 7 days a week, 365 days a year. That they are up to being driven to the limits, through traffic, in difficult conditions and safely. That they are suitable for carrying the 20-30 hazard cones, stinger, safety kit, riot shields and equipment, two big **** off kit bags and two 14 stone blokes. That they are suitable for the fitting of emergency lighting and ancilliary equipment. That they are ergonomic and comfortable to be the office and transport of a cop who will spend at least 5 hours a day in it.

I'm not sure Autocar does that particular test...

If the police bought the cars on the basis that the manufacturer says it can do this that and the other, and that some greasy car journalist thought that it was quite nice for him and his dog, rather than carry out extensive and exhaustive tests to make sure that they represented the best value and service for the taxpayer who funds them then THAT would be a waste of tax money.