Performance differences

Last weekend I test drove an Evoque and of course fell in love!

It was a manual Pure with the 150hp engine and I was pleasantly surprised by the perfomance of the car. It didn't feel at all underpowered, and I would be more than happy to live with it.

But then I had a look at the official perfomance figures of the different Evoque models and I found them rather puzzling. These figures are taken from the Swedish LR site but I guess they're the same everywhere.

eD4 / MAN / 2WD
0-100 km/h 11,2 sec
TOP SPEED 180 km/h

TD4 / MAN / 4WD
0-100 km/h 10,8 sec
TOP SPEED 185 km/h

So the 2WD version is almost half a second slower to 100 km/h? And that despite weighing 75 kg less. I guess that better traction off the mark for the 4WD version may account for the acceleration difference, but why has the 4WD version a higher top speed? Different gearing?

And this acceleration gap actually increases when the 150hp engine gets its power down via the automatic gearbox instead of a manual one - the auto version being more than one second quicker up to 100 km/h.

TD4 / AUTO / 4WD
0-100 km/h 9,6 sec
TOP SPEED 182 km/h

I know that autos are much more efficient nowadays but it's not often you see official 0-100km/h figures where the automatic version is more than one second quicker than the manual. But the manual version gets slightly better mileage and top speed.

It's the same thing with the 190hp version but the acceleration difference is actually even bigger.

SD4 / MAN
0-100 km/h 10 sec
TOP SPEED 200km/h

SD4 / AUTO
0-100 km/h 8,5 sec
TOP SPEED 195km/h

Actually this means that the 150hp auto version accelerates to 100km/h 0,4 sec faster than the manual 190hp version! Can't be just differences in gearing, can it?

I have read that some think the 6-speed auto gearbox is rather ancient and wants a new 8-speed box in the Evoque, but the existing 6-speeder seems to be superefficient or at least superquick, don't you think!

But what is the reason for the all auto Evoques accelerating so much quicker than the manual versions?! I would love to know! And someone on this fantastic forum must know!

/Ackel

I have the TD4 manual but I had my test drive in the SD4 manual and to be honest other than the extra exhaust I can't see where the extra 1k went.

Is the TD just a remapped SD anyway?

Mostly engine mapping and twin exhaust, plus some differences in injector pressures. Pete has remapped a TD4 close to the SD4, see his thread on this.

Manual is slightly higher geared, and you have to declutch between shifts losing time and accel, but manual more economical and a nice gearbox. I'd have gone for an even slightly longer top gear for better economy on motorways.

What gets a car to 60mph is engine power which (in Watts) is the torque (in Nm) * 2 * PI * engine speed (revs/sec).

Torque varies with rpm and peak power tends to be achieved a little below peak rpm but is always in the higher rpm ranges, so it follows best performance is achieved by keeping the engine working in those higher ranges for as much of the time as possible. That's down to gearing and a gearbox with closely spaced ratios but it comes at the expense of additional changes being required and there's a trade-off.

There will be at least 2 changes to 60mph and that is where the automatic can gain over the manual by making the changes more quickly which minimises the dead time when no power is being delivered to the wheels. This is even more the case in cars with double clutch gearboxes which can change gear very quickly by simply releasing one clutch and engaging the other. Someone driving a manual is doing well to get the change down to much below 1 second.

(30-01-2012 07:27am)mark_n Wrote:  There will be at least 2 changes to 60mph and that is where the automatic can gain over the manual by making the changes more quickly which minimises the dead time when no power is being delivered to the wheels. This is even more the case in cars with double clutch gearboxes which can change gear very quickly by simply releasing one clutch and engaging the other. Someone driving a manual is doing well to get the change down to much below 1 second.

Yes, I understand that the time needed to change gear will affect the acceleration time, and in ordinary use an automatic gearbox will often be much quicker than when the driver manually changes gear. But normally an auto has effect losses compared to a manual, and when manufaturers and car magazines are doing acceleration tests they usually get better times with the manual gearbox. I know that the gearing of the car will of course affect the official acceleration times, especially so if it means that automatic version will reach 100km/h with one less gear change than the manual version.

The thing with the Evoque is that the acceleration times are so consistently much quicker with the automatic gearbox than the manual one, in a way I don't think I have encountered before.

(30-01-2012 07:27am)mark_n Wrote:  Torque varies with rpm and peak power tends to be achieved a little below peak rpm but is always in the higher rpm ranges, so it follows best performance is achieved by keeping the engine working in those higher ranges for as much of the time as possible. That's down to gearing and a gearbox with closely spaced ratios but it comes at the expense of additional changes being required and there's a trade-off.

Whilst that is generally true for a petrol (gasoline for our US friends), it isn't the case for a diesel - where peak torque is typically in the 1500-2200 rpm range (i.e. with a start point barely above idle) with maximum power much higher up. Plotted on a graph - a typical petrol engine will have power and torque plots that rise roughly together, on a diesel the torque curve will be quite flat - with the maximum achieved within a limited rev range.

For the auto versions of the RRE the ratios are lower/closer together (including final drive) and that results in snappier perormance at the expense of fuel consumption at motorway cruising speeds - though not by much in the real world it seems.

take into account published manufacturers figures are not always 100% accurate.

1)eD4 is slower vs TD4 due to different settings (140cv /150 cv, gear ratio, etc)
2)Manual is slower vs Auto due to different 1st/2nd gear ratio (manual has shorter )

1happydream

(30-01-2012 12:21pm)1happydream Wrote:  1)eD4 is slower vs TD4 due to different settings (140cv /150 cv, gear ratio, etc)
2)Manual is slower vs Auto due to different 1st/2nd gear ratio (manual has shorter )

1happydream

Does that mean the manual has an extra gear change to hit 60?

The 0-60 on my civic type r was affected by this it was still quick but most other hot hatches of its time hit 60 in 2nd whilst the civic took 3rd.

0-60 is a rubbish measure of real world driving performance anyway.