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you & your car

I have just spent a huge amount of money on having routine maintenance done on my 2006 Honda Civic at the dealership. This car has an onboard computer that monitors the car's usage and automatically tells me when maintenance is due, as well as what kind of service is required. As a retiree I don't use the car every day and its mileage accumulates slowly, about 10,000 km a year. The dealer keeps notifying me that, according to their records, the car is due for maintenance even when the onboard computer says that the interval between maintenance obligations is just 50 per cent expired. When I question the dealership about this they say that the car still needs maintenance on a periodic basis, and that overrides what the onboard computer says. I would be grateful if you could tell me if they are causing me to pay for unnecessary work. – Steven in St Catharines, Ontario

They probably are. This has become a common complaint among consumers. I've had comments in the past week alone from Honda, Hyundai, Kia and Volkswagen customers – from different parts of the country and obviously different dealers.

The problem appears to be dealers trying to make profit centres from their service departments. Manufacturers go to great lengths to test their vehicles during development and arrive at recommended service intervals, which are published in the owner's manual.

They commonly include normal and severe service. The latter goes under a variety of names but does not necessarily mean extreme hard use, but just as often infrequent use.

My recommendation is to ensure you follow this schedule for maintenance and keep all records to ensure you are covered by warranty. The next time the dealer calls, remind him you are following the service schedule recommended by the manufacturer and will be in touch when it is time for a visit.

Getting more power

What is the difference between turbocharging and supercharging? – Al

They both force more air into the engine in order to generate more power, but do so by different methods.

A turbocharger consists of a pair of vanes or propellers on a common shaft. One is positioned inside the exhaust system and the other the intake system. As the exhaust gases exit the engine, they cause that part to spin. This in turn causes the other end, located in the intake stream to spin forcing more air into the engine.

A supercharger is run by a belt or chain driven off the crankshaft. As the crank turns, it spins the supercharger, usually at twice engine speed, forcing more air into the engine.

I have simplified this to the extreme, as there is a great deal of engine management electronics and other hardware involved.

With most turbochargers, there is also an air-to-air intercooler to cool the temperature of the incoming air.

The advantage of superchargers is that they respond immediately to changes in engine speed or throttle application. The disadvantage is that they take power from the engine in order to make power.

The advantage of turbochargers is that they generate "free" power, the disadvantage is that there is generally a lag between when the throttle is opened and the turbo spins to the 200,000 rpm range where it produces force.

You are going to see a lot more of both in the coming years as manufacturers strive to generate improved fuel economy. Both superchargers and turbochargers allow more power from a small engine that uses less fuel.

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