Tow Car Tests in General

[Lutz]

Whenever I read towcar tests in caravanning magazines I am often disappointed by the little space devoted to reviewing their towing behaviour and ability. Most of the article is devoted to stuff that one can read up in any self-respecting car magazine and too little is what is of specific interest to the caravanner. When they do talk about towing performance, they usually don't comment on behaviour of the car at the limit. In fact, they often don't even mention the weight of the caravan that the car has been tested with and even if they do, it's at 85% weight ratio and not higher if the manufacturer's spec allows. Test results under such ideal conditions are not of much help to those people who are confronted with less than ideal, but still legal, ones and they have a right to know how the car performs then. Besides, inherent weaknesses will show up more clearly when driven at the limit.

Am I alone in my criticism?

 

[Zafiral]

Lutz, I know where you are coming from. Comments about how the car drives solo and interior space are readily acertainable by a test drive or a visit to a dealer.

However, the Practical Caravan tests also include some towing not on a public road including the brutal lane change manouvere which stretch the towcar more than your normal Sunday drive to the shops or a spin round the block with the salesman sitting next to you breathing down your neck.

 

[Chris_374224489]

Lutz

I agree completely.

I also dislike the towcar of the year which is based on price point & will always favour the lighter cars with the bigger engines which are asked to pull less weight than the heavier car at the same price point. This might mean that if the heavier car were given the same caravan as the lighter car it might be a better tow for the same money. It isn't tested that way - they just assume we all tow the heaviest caravan that we can which for me at least is simply wrong.

 

[Lutz]

The thing is, though, that they don't test with the heaviest caravan that the car can tow. A car with a kerbweight of, say, 1500kg and a towload limit of also 1500kg is invariably tested with a 1250 or 1300kg caravan. Such an outfit may be perfectly acceptable, but when called upon to tow at its 1500kg limit, it fails miserably. Another car of the same weight class may, however, still be quite comfortable under the same conditions. It would be worthwhile having the magazine point this out.

 

[Dustydog]

Lutz

I think PC Mag should ask you to do the long term tests on their tow car fleet. You are hitting all the right buttons for me.

Until recently very few people knew the BMW X5 needs an uprated cooling fan for towing. Bizarre for a vehicle of its size and cost.

I wonder how you will manage with the Golf and your 1800kgs beast in tow??LOL.

Cheers

Dustydog

 

[Lutz]

Lutz

I think PC Mag should ask you to do the long term tests on their tow car fleet. You are hitting all the right buttons for me.

Until recently very few people knew the BMW X5 needs an uprated cooling fan for towing. Bizarre for a vehicle of its size and cost.

I wonder how you will manage with the Golf and your 1800kgs beast in tow??LOL.

Cheers

Dustydog

Golf and 1800kg beast?

 

[marlot]

In the bigger tow tests, I noticed that if the caravan loaded to MTPLM was less than 85%, they put the extra weight in the tow car. That may be fine for acceleration and braking tests, but its hardly going to be fair for the lane change test!!!!

In the light and middle weight categories, I think it would be much better to test a group of similar cars with identical caravan loads (at around 100% of kerbweight).

I'd love to see a Mondeo, a Passat, and a CR-V tested side by side with a 1500Kg caravan - much more realistic of the sort of question that needs to be answered.

You can't do that with the heavy cars as you can't get heavy enough caravans (eg. a discovery weighs 2.7 tonnes unladen!)

 

[Dustydog]

Golf and 1800kg beast?

Anything's possible!

 

[Lutz]

Lutz

I think PC Mag should ask you to do the long term tests on their tow car fleet. You are hitting all the right buttons for me.

Until recently very few people knew the BMW X5 needs an uprated cooling fan for towing. Bizarre for a vehicle of its size and cost.

I wonder how you will manage with the Golf and your 1800kgs beast in tow??LOL.

Cheers

Dustydog

I did say legal outfits. There wouldn't be any point in testing something that's illegal in the first place. No Golf is legal with a 1800kg caravan behind it.

 

[xtrailman]

Maybe if each car had to tow different weights, say starting at 1300kg, then increments of 100kg up to it legal limit.

Because as it is the tests are meaningless, my van comes in at 1333kg, but maybe i am thinking of going heavier say 1500kg, so if the tests use varying weights, we should all have some useful feedback.

As it is the tow car of the year means nada.

 

[Zafiral]

Unless they actually tow your own caravan with the various cars then the tests will not be conclusive, as some caravans may match better with certain cars than others.

For example Baileys may prefer a higher car owing to their straighter fronts. Swifts with a more sloping front may prefer a saloon type car, who knows.

 

[Lutz]

You have a point regarding your own specific configuration, Zafiral, but I think anything would be an improvement over how they test today. At least one would get a bit closer to uncovering weaknesses which become apparent when towing closer to the limit.

 

[marlot]

Maybe if each car had to tow different weights, say starting at 1300kg, then increments of 100kg up to it legal limit.

Because as it is the tests are meaningless, my van comes in at 1333kg, but maybe i am thinking of going heavier say 1500kg, so if the tests use varying weights, we should all have some useful feedback.

As it is the tow car of the year means nada.

Even better than my suggestion

 

[Zafiral]

Lutz, the clubs and PC mag are all stuck in a quandry of recommending 85% and then testing cars beyond that. Even at 85% some cars show some stability issues, so all we can do is read between the lines.

 

[Lutz]

I don't see any contradiction between recommending 85% weight ratio but testing beyond that. The testers must be fully aware that not everybody sticks to this recommendation, so they shouldn't close their eyes to relatively common practice. Besides, testing at the limit may cause them to rethink about the sense or otherwise of a blanket 85% recommendation.

 

[Gafferbill]

I should not really join in this discussion and I expect to be shot down!

My point of view is that 85% weight ratio IS the maximum limit.

Using the old maxim. 'Have the smallest caravan for your needs

My towing weight ratio is 60% with a 6.2mtr Swift

 

[DevonshireDave]

As we all know the 85% match is a guide, albeit a sensible one. How many of us actually weigh our vans on a weighbridge to check it's loaded weight before we go off on our travels? Not many I bet.

I, like many, will load their vans sympathetically and try and put all the heavy items in the towcar. Lutz has a very valid point though. Some folks have to tow at in excess of the 85% ideal and it would be nice to know how these cars perform when challenged with a match closer to what many will really encounter.

Dave

 

[Lutz]

Nobody seems to know how the 85% weight ratio recommendation was ever established and it appears to be totally arbitrary. It could just as well have been 80% or 90% or some other figure. Also, without testing to the limit, no-one even knows whether such a blanket recommendation is applicable to all cars or whether some are more sensitive than others.

None of the clubs and organisations that publish the recommendation have ever verified its validity, so it is perfectly legitimate to question whether it makes any sense as it stands without any differentiation.

 

[xtrailman]

The CC sponsored bath uni during 1993/95, the research showed that a instability accident DECLINED markedly the more the car weighed in proportion to the caravan.

Source practical caravan april issue p72

 

[Lutz]

There's no denying that an unfavourable weight ratio can adversely affect stability, all other conditions remaining equal, but no-one has proved that the risk of an accident increases disproportionately to an unacceptable level once the weight ratio exceeds 85%.

 

[xtrailman]

i think its best not to get hung-up by the 85% recommendation, but rather concentrate on towing with ratios below this figure.

 

[Lutz]

Who says that an outfit cannot be perfectly manageable at 90% or even 95%?

 

[xtrailman]

But who would want to compromise safety, by towing to the limit?

Even when a uni has researched and printed its conclusions, you still insist that the advise is flawed?

 

[Lutz]

The university report only says that accident risk increases with, amongst other things, weight ratio. The report itself does not make any recommendations regarding an acceptable weight ratio limit. There is no mention of any specific value, whether 85% or anything else, as being critical.

In Germany there is a legal 100% weight ratio limit for towing at 100km/h (62mph). If you exceed 100% then you are limited to 80km/h. It can be safely assumed that the powers-that-be didn't draw these limits out of a hat when the law was written, but based them on sound judgment. If that is the case, how does one reconcile their findings with a 85% recommendation?

 

[ProfJohnL]

I think most people on this forum know my views about the 85% figure, so I will not repeat them in detail here, but I do agree with the OP that that the magazine reviews are perhaps short selling the abilities of some towing vehicles by sticking to this silly arbitrary figure.

I think the towing tests should be done under three separate conditions subject to none of them exceeding the manufacturers limits:

85% (To satisfy the faithful followers)

100% (As there at least an understandable relationship)

and at the outfits legal maximum (To prove the manufactures specifications)

It is likely that what ever formula the magazines use, someone is likely to criticise it for some reason or another.

The test caravan used should always be loaded to give the maximum nose load for the outfit.