Road versus track testing of normal cars

Posted on January 18th, 2004 in Opinion by Julian Edgar

For years I’ve thought that magazines that test road cars on the track are deluding themselves. The conditions on a typical race track are simply so far away from real roads as to make the judgements gained on a track worse than useless. And I deliberately say ‘worse’ because in many cases I believe that the outcome of a process that involves track testing road cars – and then writing a road test on that car – can be very misleading.

A road car is a car designed for roads. You don’t test a Formula racing car by driving it to the local shops and seeing how many groceries can be fitted in, so why test the handling of a road car on a race track? Race tracks are invariably smooth, they have one-way traffic, they have run-off areas (which immediately makes a nervous car feel less twitchy!) but most importantly of all, the driver always knows exactly the radius of the next corner, the length of the straight, what the blacktop does following a crest.

Simply, on a track you’ll enjoy a car more inclined to oversteer, with much faster responses, and with quicker steering than would ever be pleasant – and safe – on a road.

Click for larger image
Well, those are my thoughts – but when an opportunity came up recently to talk to Barry Lake about them, I jumped at the chance. Barry Lake is amongst Australia’s most experienced motoring journalists. He’s also participated in motorsports – including major races – and has been involved in numerous road and track tests of cars. He’s a former editor of ‘Motor’ magazine, and still participates in that magazine’s major tests – for example, tyre comparisons, which include much track work.

I put it to him that the track is not an appropriate place to test road cars, so why go there?

“Most people, most of the time, will never get anywhere near a performance car’s limits,” he said. “They probably don’t care how it handles and brakes. But there are people who are going to go out and somewhere, sometime drive the car to its limits – or near. I think it’s important to know – and to keep reminding the manufacturers – that if you’re going to build a car with performance, it’s got to have the handling and the braking to go with it.

“And you can’t test that on the road, not legally and not easily.

“Driving a road car around a race circuit is not always ideal in that the surface is different from what you often strike on the road, but you still have the opportunity to gauge how well a car handles, how well it brakes – and therefore how safe it’s going to be in extreme conditions.

“But it’s not ideal; it’s not perfect. It’d be nice if you had a closed road that was more like a real-world road – and there are places like that. At the Driver Education Centre of Australia at Shepparton, they’ve got a nice little loop there that is deliberately made just like a country road.”

The clearest indication of the track testing fallacy is that you can make a car faster around a track – while at the same time decreasing its real road handling abilities!  I put this to Barry Lake.

“I can think of an example of that,” he said. “I’ve always liked Clubman cars – like the Lotus Super Seven. I actually planned to buy one and I had ideas of going in Targa Tasmania [a bitumen road rally held on very demanding (real!) roads] . I competed in Targa Tasmania in more normal cars but whenever there was a Clubman car around, I watched them with great interest.

“And these cars – which are absolutely sensational around a race circuit – were in a lot of trouble in Targa Tasmania, where they had bump and ground clearance problems, bottoming-out on dips. I put a lot of time and thought into how you would modify it to make it better on the road – in which case it would not be as good on the circuit.”

And what about cars – like the Impreza WRX – that on the road are confidence-inspiring and fast, but on the track often incline to understeer?

“That’s where the skill and the experience of the tester comes in relating what it does on the circuit to what it does on the road ,” Barry said.

“If you’re writing in a story – and you want the people to really understand – you would explain. You would say that on the circuit it doesn’t work as well because of that.

Click for larger image
“When you’re getting into more specialised cars, you have to look at it differently. When you’re talking just everyday cars that are not highly modified, I think that the track is probably more relevant. When you’re talking cars that have modified suspension you’re going to extremes, and there does become a greater difference between circuit and on-road performance.

“Going back to the WRX, a really good example of that is the STi version. I drove one of those recently on some country roads and it was absolutely diabolical. It was bouncing around so much that you couldn’t keep your foot steady on the accelerator. You couldn’t make smooth gear changes. It was bouncing so much that it didn’t have grip.

“But you put that car on the race circuit and it’s way better than the normal WRX. But on that sort of road, the WRX is better than the STi.

“It does get back to your original argument that testing on the race circuit alone is not necessarily indicative of what the car is going to be like in the conditions that somebody’s going to be driving it in.

“You should also go out and drive it on the country roads as well…”

4 Responses to 'Road versus track testing of normal cars'

Subscribe to comments with RSS

  1. Bob Wilson said,

    on September 18th, 2007 at 11:00 pm


    I’ve been road testing my 2003 Prius, NHW11, since I bought it nearly two years ago. My primary interest is mapping the fuel consumption as a function of speed and other variables. So far, this has identified some sweet speeds, 60 kph (38 mph) city and 105 kph (66 mph), gasoline brands, wheel alignment, warm-up practices, route planning, hill climbing, and transaxle lubricants. Every test succeeded even when they came back with “don’t do that again, ever!” But I’m still having difficulty getting a stable, math model that integrates all of the data:

    Controlling and tracking all of the variables is not trivial and I’m beginning to wonder if track testing suffers from the same problems I’m running into on the road . . . too many variables resulting in different results depending upon preparation, weather and track conditions. How do you handle making sure your results are reproducible on the track and subsequently the road?

    I am leaning towards recording everything, all trips and as much data a possible and then trying to do a multi-variable analysis. With enough data, hundreds of megabytes with as many variables as possible, it should be possible to have software look for correlations. In short, I’m thinking of trying to harvest an engineering model from a huge mass of data points. This is driven my by frustration that every trip is potentially a test but I need to reduce the labor associated with reducing the data. Have you run into similar testing approaches?

    Bob Wilson

  2. Julian Edgar said,

    on September 19th, 2007 at 7:48 pm

    Bob, if your aim is “mapping the fuel consumption as a function of speed and other variables” you are going to have, I would have thought, hundreds of variables. In climatic conditions alone, I can think of many.

    Obviously a public road has more variables than a racetrack, and if the road testing is done over a long period, even more variables will come into play.

    In short, I cannot actually see an outcome – but for what it’s worth, the road would be better than the track!

  3. Bob Wilson said,

    on September 19th, 2007 at 10:52 pm

    Thanks Julian,

    I have been trying to use road test data to ‘rediscover’ the drag formula for my model Prius, 0.42*(V**2) + 190 N. My road testing includes multiple “neutral” rolling tests in both directions and the results have been mixed. Short of a vehicle dynometer and wind tunnel testing, I’m trying to figure out how a layman might get a usable, vehicle drag formula from the road. Right now, I agree that there are too many variables.

    By integrating the drag formula over distance and adding the ‘overhead’ energy, one comes up with a pretty useful, theoretical MPG vs MPH curve. Differences between road tests and this drag defined, limit, identifies where improvements are needed or better than expected performance, ‘sweet spots’ can be found.

    Within tolerable error, the road test MPG vs MPH has been reproducible and revealed or validated major factors: (1) engine oil level needs to be 75% full and never over F, (2) tire pressure closer to side wall maximum, (3) importance of low-power, rolling warm-up, (4) auto-off, control law boundary at 67 kph, and (5) transaxle MG1 rpm speed limit at 112 kph.

    I’m not giving up on road testing but was looking for ideas on how it might be used to validate or derive the drag formula coefficients.

    Bob Wilson

  4. Julian Edgar said,

    on September 20th, 2007 at 5:58 am

    Many years ago I tried coast-down tests on a flat windless road to try to ascertain car drag coefficients. The results were all over the place so I gave up.