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lou's garage

Hi, I have a Passat 2013 Wolfsburg model. I have recently noticed a difference between the real speed of the car and the speed indicator reflected by the speedometer like 10 per cent compared to speed on my phone app. I took the car to the VW dealership to remedy the problem, their answer was it would cost $800 to detect or diagnose the problem.

Any advice? – Aley G

GPS’s calculate speed using distance travelled over time. Your phones consumer based built-in GPS typically has a stated accuracy of 1-3 metres, I would not trust your phone for a reading finer than 10 per cent accuracy. However, as you drive a steady speed for an extended period your GPS will slowly fine tune the reading and provide you with a more accurate reading. If you research speedometers you will also find many reports stating that auto manufacturers err on the side of inflating your speed. European laws state that a speedometer cannot read slower than actual speed but are allowed to read 10 per cent above actual speed. There are no specific speedometer laws in Canada, but considering your vehicle is of German design I will assume it follows those rules. Your vehicle calculates its speed by using rotational speed information from the four wheel speed and transmission sensors. Any variance in tire size will cause errors, but generally most are assumed to be within 3-5 per cent. So, if you are sporting the correct tire size for your vehicle, I believe that you are probably within the factory allowed speed variance, quite possibly not the absolute correct speed, but still within manufacturer-allowable limits.


We own a 2010 Lexus RX450h. We’re thinking of leaving it stored in our garage in Palm Springs next summer from May to October. Temperatures can reach 110F and higher for brief periods. Is it safe to store at such temperatures or should I store it for a fee in an A/C storage facility? – Peter U

Interesting question. Here in Canada, most of you only want to know about cold weather storage, therefore I had to do some research for this one. Generally, most manufacturers of hybrid vehicles claim that their vehicles have an operational range from approximately -30 to 60°C (-22 to 140 °F). That seems a little extreme to me, but regardless of whether or not these numbers are completely accurate, we can easily see that your storage temperature falls well within that range. The fact that it will be inside protected from damaging direct UV sunlight also bodes well for you. I imagine that most vehicles in the southern states sit outside baking in the sun all summer long. Given this, I don’t believe there is any need to procure a temperature-controlled storage facility for that period of time. If your garage has decent ventilation, then that would be even better.

Lou Trottier is owner-operator of All About Imports in Mississauga. Have a question about maintenance and repair? E-mail globedrive@globeandmail.com, placing “Lou’s Garage” in the subject line.

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