Cadillac BLS Owner's Manual

Contents

Cadillac BLS Owner's Manual Manual pdf 158 page image

158 Starting and drivingEconomical motoringFactors affecting fuelconsumptionThe fuel consumption of a car is greatlyaffected by driving conditions, climate, roadconditions, speed, driving technique, and soon.Running-inFuel consumption may be somewhat higherduring the running-in period (the first3100-4350 miles/5000-7000 km) thanstated values.Weather conditionsSummer temperatures give better fueleconomy that winter ones. The differencecan be as much as about 10 per cent. Con-sumption increases in cold weatherbecause the engine takes longer to reach itsnormal operating temperature. The trans-mission and wheel bearings also takelonger to warm up. Even distance affectsconsumption: short journeys of three tofive 3 to 5 miles (5-8 km) do not give theengine enough time to reach its optimumtemperature. Wind conditions also have amarked effect on consumption.How to read the diagram (the followingexample relates to petrol-engined cars):If fuel consumption with the engine at normaltemperature is 28 mpg (10 l/100 km), theactual fuel consumption 3 miles (5 km) afterthe engine has started from cold will be:– 23.5 mpg (12 l/100 km) at outside temp.of +20 °C (increase of 20 %).– 17.7 mpg (16 l/100 km) at outside temp.of 0 °C (increase of 60 %).– 14.1 mpg (20 l/100 km) at outside temp.of –20 °C (increase of 100 %).It is clear from the diagram that both dis-tance driven and outside temperature havea significant impact on fuel consumption,after a cold start.If the car is normally driven on short jour-neys of 3 to 5 miles (5–8 km), for exampleto and from work, the average consumptionwill be 60-80 per cent above the normallevel.Driving techniques• To achieve the best running economy,with regard to fuel consumption and gen-eral wear, the car must be serviced regu-larly.• High speed, unnecessary acceleration,frequent braking and much changingdown all give higher fuel consumption.• Frequent gear changing in traffic, startingin cold weather, the use of studded tyresand roof racks, and towing a caravan allincrease fuel consumption.Percentage increase in fuel consumptionof engine starting from cold compared toengine at normal temperature460_OM_MY09.book Page 158 Wednesday, April 2, 2008 10:32 AM