A lack of common sensor
I ama retired electronic engineer and I worry about vehicle speed being measured by in-road sensors (transducers), because there will be an error factor involved. Transducers are proximity sensors designed to work in one dimension only, in this case horizontally. They have been commonly used throughout industry for decades, usually as lumps or indentations on spinning rollers as they pass a fixed transducer coil. But, as the roller bearing wears, the transducer becomes inaccurate, because another dimension is added. The problem with using them in roads is that cars have additional vertical movement from their suspension, which will change the trigger point for the transducer. So the ideal speed transducer would be a dead-flat road for vehicles with no suspension movement. This may help explain why some freeway speed cameras are always in dispute. It is interesting that the overhead speed displays on several freeways are usually out of service, so how bad are they?
Barney Rumble, email You raise a very interesting point, and one we had not considered. Perhaps other readers have more to add. PULSAR FADING I own a 2005 Nissan Pulsar N16 which is approaching 100,000km. The manual says the timing belt needs to be changed but my local garage says they don’t have a timing belt. Is this correct?
KenLongbottom, email The cam belt is probably the most important service item in any car, because if it fails the engine is likely to disintegrate when valves hit pistons. Get it changed. Buy the parts from a Nissan dealer if necessary and give them to your mechanic. MOVING THE PEOPLE I have been told you might be able to help me as I amlooking at buying a people mover for a small business I have started. I amwanting to spend around $8000 and I like the look of the Holden Zafira 2003. What do you think about this, or do you have any others you would recommend?
Simon Main, email The Zafira is fine. More like a baby wagon than a people mover, which is why it was not a big hit in Australia. If you need something bigger, the best value is a Kia Carnival. THE i30 HAS IT I saw the new Hyundai i30 and was looking at the Hyundai website where I saw that the Elantra has the same 1.8-litre engine, with the same 110kW/178Nm. Is this the same car with a new body? And a second question, what do you think of base model Veloster 1.6 litre?
Maria Salsa, email The i30 is completely new and the chassis is not related to the Elantra. The Veloster is a fun little car and great value. AMG-WHIZZ I have a 2007 BMW535i fourdoor sedan and our lease is up. We are looking at the Mercedes-Benz C63 AMG. Could you let me know what you think about it as a family car?
GabbyFarrugia, email The C63 is a ripper car. Definitely a step up from a 535 and something that you will really enjoy. But not as big in the cabin as a 5 Series. NUMBERSGAME I amlooking to buy a used Renault Megane RS 250 Cup Trophee with about 4000km on the clock, but I have been informed that the RS 265 is now available in Australia. Is it worth spending the extra money to purchase the 265 or stick with the 250?
Michael Balliro, email Save the money and go with the 250. The 265 is all at the top end and otherwise the cars are pretty much identical.
Sign of the times: Overhead speed displays
may be hit and miss