http://citycyclingedinburgh.info/bbpress/ CityCyclingEdinburgh Forum » Topic: “Modern cars aren’t designed to go at 20mph” facts please en Sun, 05 Apr 2026 21:17:31 +0000 http://citycyclingedinburgh.info/bbpress/topic.php?id=20052&page=2#post-321514 Mon, 27 Jan 2020 11:08:43 +0000 fimm 321514@http://citycyclingedinburgh.info/bbpress/ <p>I'm pretty sure that in The Netherlands you can only park your car where markings tell you that you can, unlike here, where you can assume that you can park your car unless yellow lines tell you you cannot. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052&page=2#post-321470 Sat, 25 Jan 2020 15:20:20 +0000 Greenroofer 321470@http://citycyclingedinburgh.info/bbpress/ <p>I'd still vote for that design in Edinburgh :-). The bike lane is hugely wide (same width as the vehicle lane). I don't know my Dutch traffic signs well enough to know if the on-road bike lane is the equivalent of a UK one (i.e. everyone drives in it and parks their car in it) or whether it's a mandatory one. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052&page=2#post-321466 Sat, 25 Jan 2020 14:45:39 +0000 CycleAlex 321466@http://citycyclingedinburgh.info/bbpress/ <p>It's interesting as if that design was implemented in Edinburgh, I imagine quite a few people here would complain. The junction is done nicely but it quickly becomes advisory lanes on the outside of quite a bit of parking.</p> <p>Of course I'm sure relatively low traffic and different driver behaviour makes it more than pleasant. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052&page=2#post-321465 Sat, 25 Jan 2020 14:03:34 +0000 Greenroofer 321465@http://citycyclingedinburgh.info/bbpress/ <p>That Streetview of Utrecht is so much "Here's what you could have won". There's lots of capacity for cars, but the bikes and pedestrians are treated as (at least) equal. I had a bit of a virtual mooch around that junction: one one view there are two older women side by side, having stopped their bikes for a natter. In other there's a younger woman with a cargo/kids bike.</p> <p>But, of course, This Is Edinburgh. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052&page=2#post-321464 Sat, 25 Jan 2020 14:01:24 +0000 Rosie 321464@http://citycyclingedinburgh.info/bbpress/ <p>I mean if I moved to somewhere with only 4x4 access, I would buy a 4x4, not complain that my little low-slung runabout isn't suitable and demand the access be changed. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052&page=2#post-321463 Sat, 25 Jan 2020 13:57:09 +0000 Rosie 321463@http://citycyclingedinburgh.info/bbpress/ <p>Well if they're not, shouldn't they be, if those are the urban conditions they're going to find themselves in.</p> <p>Cars are mostly used for shopping, commuting and the school run, not James Bonding through the Alps. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052&page=2#post-321462 Sat, 25 Jan 2020 13:43:11 +0000 rbrtwtmn 321462@http://citycyclingedinburgh.info/bbpress/ <p>Entry to a 20mph zone in Edinburgh:<br /> <a href="https://goo.gl/maps/HHxFBYhYwqYehQ679">https://goo.gl/maps/HHxFBYhYwqYehQ679</a></p> <p>Entry to a 20mph zone in Utrecht<br /> (not brilliant in other ways,<br /> but provides direct comparison):<br /> <a href="https://goo.gl/maps/agot9KiwDqkyX3Ht7">https://goo.gl/maps/agot9KiwDqkyX3Ht7</a> </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321460 Sat, 25 Jan 2020 13:14:15 +0000 chdot 321460@http://citycyclingedinburgh.info/bbpress/ <p>“it's to change the street design to match the speed limit.”</p> <p>Quite so. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321458 Sat, 25 Jan 2020 12:36:30 +0000 rbrtwtmn 321458@http://citycyclingedinburgh.info/bbpress/ <p>The idea that modern vehicles can't be driven comfortably at a speed around or below 20mph is clearly [rubbish]. But (s)he's on to something. It does, often, feel like driving at the speed limit is difficult. This applies at 30mph 50mph 70mph.</p> <p>The problem is that it feels awkward to drive at the speed limit on modern roads which have been engineered to allow much higher speeds (intentionally with features to allow speed faster than desired).</p> <p>To put it more simply: modern city roads in the UK aren't designed to be driven at 20mph.</p> <p>Faced with this as the problem it becomes blindingly obvious that the solution isn't to raise the speed limit (that starts to sound really silly), it's to change the street design to match the speed limit. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321449 Fri, 24 Jan 2020 19:46:12 +0000 Morningsider 321449@http://citycyclingedinburgh.info/bbpress/ <p>30 kmph is the normal speed limit on minor urban roads in both Japan and Germany. I find it hard to believe that the boffins at Nissan, Toyota, VW and BMW would design mass-market cars that can't operate efficiently at that speed. Although I'm willing to believe this isn't much of a consideration for AMG and the like.</p> <p>I have had a good rake around for research which proves that driving at 20mph damages drive trains, but have not been able to find anything. I did find lots of advice to drivers not to thrash their cars, but that's a different matter. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321446 Fri, 24 Jan 2020 18:43:25 +0000 wingpig 321446@http://citycyclingedinburgh.info/bbpress/ <p>@Darkerside Didn't know cars had those. Sounds kind of like intake cones/ramps for supersonic aircraft, but the other way round. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321444 Fri, 24 Jan 2020 18:31:57 +0000 Darkerside 321444@http://citycyclingedinburgh.info/bbpress/ <p>I'm really replying so I can use my favourite motoring noun "swirl flaps".</p> <p>Our 1.6L petrol people-carrier is old and tired. It has swirl flaps on the engine air intakes to make the air more turbulent at lower powers, which open more as load increases until at a certain power setting they're fully open.</p> <p>Because car is old and tired, these flaps have been wired open (because they were getting stuck, and making an already underpowered car struggle to get over 30mph...). Therefore it now really doesn't like operating at certain low-power settings. 30mph is a bad notch, so I tend to sit at 27ish in fourth, rather than 30 in fifth. 20, as it turns out, is lovely in third.</p> <p>I'm not sure what conclusion to draw with respect to the broader argument. </p> <p>Swirl flaps. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321443 Fri, 24 Jan 2020 18:29:30 +0000 wingpig 321443@http://citycyclingedinburgh.info/bbpress/ <p>I always assumed noisy exhausts were a deliberate feature of these sorts of thing to try and draw attention to them, rather than an indication of them being asked to exceed their designed usage range.</p> <p>If one was performing some sports in one of these sports car things, perhaps by accelerating from 0mph to 60mph (or even beyond), what gear would one be in at the point of passing momentarily through 20mph? Could one have such a vehicle retro-fitted with a manual choke to aid them in performing non-sporting practical tasks? My flatmate in first year had a Chevette, which was a long way from being practical and sensible yet had a manual choke. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321438 Fri, 24 Jan 2020 17:46:56 +0000 acsimpson 321438@http://citycyclingedinburgh.info/bbpress/ <p>@Baldycyclists, it does sound like your car is a bit of an exception. Without knowing the model it sounds like it is more designed to go as fast as possible round a track without worrying about fuel consumption.</p> <p>As you demonstrate it's entirely possible to drive such a car within the legal limit. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321435 Fri, 24 Jan 2020 16:55:39 +0000 mcairney 321435@http://citycyclingedinburgh.info/bbpress/ <p>I of course meant braking not breaking! </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321432 Fri, 24 Jan 2020 16:17:53 +0000 Stickman 321432@http://citycyclingedinburgh.info/bbpress/ <p>“Modern cars aren’t designed to go at 20mph”</p> <p>If that is the case then modern cars are utterly unsuited to be used in cities, regardless of any posted speed limit. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321431 Fri, 24 Jan 2020 15:54:08 +0000 ejstubbs 321431@http://citycyclingedinburgh.info/bbpress/ <p>I remember one BTL commenter in the chipwrapper complaining that the then proposed rollout of 20mph limits would be totally impractical because his car couldn't get up Craighouse Road if he stuck to 20mph. A number of other BTLers did point out the purpose of the sticky-up thing beside his left thigh, and the associated pedal adjacent to his left foot. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321428 Fri, 24 Jan 2020 15:23:28 +0000 jonty 321428@http://citycyclingedinburgh.info/bbpress/ <p>The idea of an electric car 'snapping' to certain speeds is quite attractive, a sort of intuitive pedal-pressure based speed limiter. Probably quite nice on the way 'up' the speedo but a bit hard to stop it being dangerous on the way 'down'... </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321427 Fri, 24 Jan 2020 15:16:28 +0000 mcairney 321427@http://citycyclingedinburgh.info/bbpress/ <p>For a number of cars I'd say that 20mph does sit on the cusp of 2nd/3rd gear.<br /> Modern tech can make life easier and blur the "accepted wisdom" that less RPMs (without labouring the engine) = more MPGs.<br /> My current car goes into an "eco" mode between about 1500-2500 RPM where it will turn off 2 cylinders if the engine isn't labouring which means that often my fuel consumption at 20mph in 2nd gear is considerably lower (like 60-70mpg) than at the same speed in 3rd gear.</p> <p>Travelling at 20mph vs 30mph, as well as the often heralded safety aspects results in less and gentler breaking so you're getting less brake/tyre particles getting kicked up as well. It's also rather conveniently round about the speed a decent cyclist on a decent bike will cruise at on the flat so less close passes/overtakes! :)</p> <p>I don't even think electric cars have a gearbox? </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321426 Fri, 24 Jan 2020 15:14:15 +0000 neddie 321426@http://citycyclingedinburgh.info/bbpress/ <p><em>my car is geared to do 60 in 2nd gear</em></p> <p>This is the unintended(?) consequence of manufacturers desperately trying to improve their 0 to 60 figures (by removing the need for an extra gear change to get to 60). 0 - 60mph figures being an entirely arbitrary construct, presumably coming originally from motoring journos and "back in the day" the fact that most cars could reach 60mph (and sometimes not 70mph).</p> <p>PS. Am not trying to pile on, just providing some background </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321424 Fri, 24 Jan 2020 15:07:59 +0000 jonty 321424@http://citycyclingedinburgh.info/bbpress/ <p>Who's piling on? I don't think anyone's accused you of anything. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321422 Fri, 24 Jan 2020 15:05:52 +0000 Baldcyclist 321422@http://citycyclingedinburgh.info/bbpress/ <p>Yep, yep, keep piling on. It's as if I said I never drove at 20 because of it - I *always* do.</p> <p>It's just the gearing, my car is geared to do 60 in 2nd gear, so of course 20 in 3rd is going to be problematic. It's not that it can't do it, the car just lurches as if it's going to stall when it's cold.</p> <p>I'd guess the 1.3's cylynders would be coming through the bonnet if it did 60 in 2nd. Different gearing...</p> <p>(it's also 11 years old, so not as advanced electronics as newer cars, which is probably also why it only gets 27mpg) </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321419 Fri, 24 Jan 2020 14:52:04 +0000 jonty 321419@http://citycyclingedinburgh.info/bbpress/ <p>Presumably the automatic speed limiting technology coming in this decade will make it much easier to stick to the limit. A very temporary problem then. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321418 Fri, 24 Jan 2020 14:46:33 +0000 neddie 321418@http://citycyclingedinburgh.info/bbpress/ <p>Yep, my 1.3 litre petrol has no problems in either 2nd or 3rd at 20mph.</p> <p>Even in 3rd gear and low revs &lt;1000rpm, you can put your foot down, and the electronics just deals with it*... not putting too much fuel into the engine to cause labouring and not providing any acceleration either...</p> <p>*Amazing, eh? Technology is like that... just makes driving easy... </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321416 Fri, 24 Jan 2020 14:40:03 +0000 Frenchy 321416@http://citycyclingedinburgh.info/bbpress/ <p>Never noticed any problems with my big, small-engined, petrol car going at 20mph in either 2nd or 3rd gear. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321415 Fri, 24 Jan 2020 14:37:45 +0000 chdot 321415@http://citycyclingedinburgh.info/bbpress/ <p>“This seems to be quite common with petrol cars in general, as they don't have the same low down torque as diesels.</p> <p>“When I drive at 20, in 2nd gear, which is most of the time, the car frankly becomes anti social because it's revving higher, and the exhaust starts to pop and gurgle loudly. It also uses quite a lot of petrol doing that.”</p> <p>Interesting. </p> <p>So, presumably, electric cars will be ok? </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321413 Fri, 24 Jan 2020 14:35:31 +0000 Blueth 321413@http://citycyclingedinburgh.info/bbpress/ <p>I did post on here a while back that, having conducted the experiment on several occasions, driving as economically as possible (my default style) my car uses 30% more fuel at 20 than at 30, so presumably 30% more emissions too at the lower speed.</p> <p>I doubt whether anyone has tried to see if "economical" increase in speed between 20 and 30 offsets this result.</p> <p>I think the point is that generalisations can't necessarily be made one way or the other. But we know there is a fair degree of pumping losses in a fourstroke motor at low revs. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321409 Fri, 24 Jan 2020 14:24:25 +0000 gembo 321409@http://citycyclingedinburgh.info/bbpress/ <p>Mrs Garto has no problem driving at 20mph in an automatic.</p> <p>This is a valid counter argument to the councillor.</p> <p>The car feels slow to the human but trhe car does not care </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321408 Fri, 24 Jan 2020 14:16:54 +0000 Baldcyclist 321408@http://citycyclingedinburgh.info/bbpress/ <p>"fossil-fuelled vehicles have gears"</p> <p>I quite enjoy watching the queues that form behind me when I'm driving at 20 through the next town.</p> <p>However the point about wheather cars are geared to do is fair.<br /> I have small, big engined sports car, and if you drive it at 20 in 3rd it just stutters almost to the point of stalling, especially when cold. This seems to be quite common with petrol cars in general, as they don't have the same low down torque as diesels.</p> <p>When I drive at 20, in 2nd gear, which is most of the time, the car frankly becomes anti social because it's revving higher, and the exhaust starts to pop and gurgle loudly. It also uses quite a lot of petrol doing that. </p> http://citycyclingedinburgh.info/bbpress/topic.php?id=20052#post-321404 Fri, 24 Jan 2020 13:15:30 +0000 wishicouldgofaster 321404@http://citycyclingedinburgh.info/bbpress/ <p>I must be really good at driving as I find it easy to keep to 20mph and my car seems to cope just fine. </p>