Aerodynamically speaking

[woofy]

Hmm the 95RON thing will certainly throw out some figures. Mazda probably did better with their petrol 6 when they were tuned for 95 not 91. Similarly the RS wouldn't be as happy on 95 as 98.

[Gerrycan]

Hmm the 95RON thing will certainly throw out some figures. Mazda probably did better with their petrol 6 when they were tuned for 95 not 91. Similarly the RS wouldn't be as happy on 95 as 98.

I thought that was bit unusual too, but it may just be a journalist error applying a comment beyond its intended context.
Journalists are only human...reportedly.

[pologti18t]

If you want to fiddle with aerodynamics have a look at Julians articles (some involve a Roomster)

AutoSpeed - Undertrays, Spoilers & Bonnet Vents, Part 1
AutoSpeed - Undertrays, Spoiler & Bonnet Vents, Part 2
AutoSpeed - Aero Basics
AutoSpeed - Blowing the Vortex, Part 1

[GTR27]

Would explain Hyundai's good figures that no one can seem to achieve (I find that most Hyundai drivers will put whatever is cheapest in there). Explains a lot of results really.

[Gerrycan]

If you want to fiddle with aerodynamics have a look at Julians articles (some involve a Roomster)

Julian Edgar is my hero! I have followed his motoring adventures and writings for years.
His interests pretty well mirror everyone of mine, the difference being he gets off his arse and does something (everything). a true genius in my opinion.
It is a damned shame for the public that he was ostracised by manufacturers from further car appraisals for being too honest and open in expressing his views.
Must get his book on car aerodynamics for Christmas.

[Gerrycan]

Would explain Hyundai's good figures that no one can seem to achieve (I find that most Hyundai drivers will put whatever is cheapest in there). Explains a lot of results really.

Too funny, I was a Hyundai owner for many years so that explains everything
I think there are a couple of reasons for the Hyundai's relatively poor real consumption. 1) For a number of years they just lied (Note American class action and settlements) 2) Nowadays, in order to appear to have good performance, the examples I have driven have sensitive throttles so with great care you can achieve reasonable economy but 'normal' driving can be quite punishing on consumption.

[GTR27]

Prob explains why I get as good or better from a lot of vehicles as I only use 98. Except in our jazz. I think 7 is the worst I have seen, for flogging it relentlessly.

Turbo cars vary a lot more between flogging and gentle. Just have to get the missus to realise that haha. I can see 10+ with her driving, she is a lead foot :p

[Gerrycan]

Same with my wife.
I have no issues with accelerating with reasonable aggression, it is socially responsible, the engine is operating more efficiently and the Octy 3 2nd gear is fairly long anyway. From around 3000 to 3500 rpm you can comfortably short shift to 4th or 5th for maintaining urban speeds economically.
She likes to drive around in 3rd which is fine and hardly noticeable with the smooth petrol engine but it kills consumption. I have learned to stay quiet. Open road driving, no problems.

[Gerrycan]

Maybe it will be of interest to you and to others that there were some cars designed by Czechs, which had even lower coefficient of drag than the Golf anreven B200 you've mentioned. So, they could probably do a better job in the aerodynamics on the new Octy, if they had a good reason for it.

Just Google Tatra 77a. It had a drag coefficient of 0.212 back in 1935.

Speaking with an even more senior citizen than myself recently about our respective cars, as you do (his is a BMW).
The topic turned to Skodas in general and he said that he remembered their first foray into the Australian market, his mate had a rear engine job. Initially I thought he was talking about a 110 but turns out it was the much earlier Tatra 77 and I was better informed on this than I would have been without this thread.
He remembers it as really big but a bit too heavy for the power of the engine.

[wai]

The vehicle travels nowhere. It goes for a 20 minute spin on a chassis dynamometer - the same kind of rolling test bench used to measure power (kW) and torque (Nm) figures.

And if you have ever watched a test being done, you will see there are points where the "chart" has to be stopped because the vehicle being tested has no way of ever catching up. And I am not talking of tiny engined cars. Back in the late 1970's, I worked for the DMT and one project involved having two vehicles (202 Kingswood and 202 Torana) tested by the EPA. For both vehicles, the chart had to be stopped to allow the vehicle to catch up.

Most manufacturers achieve these high CD values with many "tricks". The wipers are removed; the external mirrors are removed; the road wheels (and ventilated brakes) are stationary; the radiator intake is blanked off; brake ducts are blanked off; any external antennae are removed; etc. Now they do not remove all, but they do all do something to get the best value.

In the real world, you have turbulent air, and the direction is not always the best. You have a whole lot of other factors that come into it.

All a CD value does is give you SOME idea as to its efficiency, however unless you know how it was achieved, it does not tell you much. It's a lot like fuel economy figures, and ANCAP ratings. They do not always tell the whole story.