Cars & Driving

Running costs and technical questions about cars: what a trip costs in fuel, how a new tyre size changes the speedometer, and how long charging an electric car takes.

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Acceleration Time Calculator Estimate how long a car takes to reach a target speed from its power and mass, in kW, PS or hp, with the times to 50, 100 and 130 km/h. Car Depreciation Calculator See what a car is worth each year at a yearly depreciation rate, or find the rate from the purchase and the current price. A table and a chart show the value. Car Running Cost Calculator Add a car's yearly fuel, insurance, service, tyres, tax and depreciation, then get the yearly total, the monthly figure and the cost per kilometre. Compression Ratio Calculator Work out an engine's static compression ratio from the bore, stroke, combustion chamber, piston dish or dome, head gasket thickness and deck clearance. Engine Displacement Calculator Work out an engine's displacement in cc and litres from its bore, stroke and cylinder count, or the stroke from a known cc, with the compression ratio. EV Charging Time Calculator Estimate how long an electric car takes to charge from its start to its target charge, plus the grid energy, the cost and the range added. AC and DC. EV Range Calculator Work out how far an electric car goes on one full charge from its battery size, usable share and kWh per 100 km, with the range at each charge level. Fuel Cost Calculator Work out the fuel and cost of a trip, the cost per person and per km, or your real L/100 km and mpg from a fill-up. Metric, US and UK units. Fuel Injector Size Calculator Find the flow each fuel injector needs, in cc/min and lb/hr, from target power, BSFC, injector count and maximum duty cycle. Checks an injector you have. Gear Ratio and Speed Calculator Find the road speed in each gear at a given engine speed from the tyre size, gear ratios and final drive, and the rpm needed for a speed in top gear. LPG vs Petrol Savings Calculator Compare LPG (autogas) with petrol per 100 km and per year in your currency, and find how far and how many months the conversion kit takes to pay back. Speedometer Error Calculator See how far the speedometer and odometer are out after a tyre change: the speed shown at 30 to 130 km/h, the km really covered, and the UN R39 check. Stopping Distance Calculator Work out the total stopping distance at any speed: reaction distance plus braking on a dry, wet, snowy or icy road, with a table from 30 to 130 km/h. Torque and Power Calculator Work out power from torque and rpm, or torque from power, in kW, PS, hp, N·m and lb·ft. A rev table or a pasted torque curve shows the peak power. Two-Stroke Oil Mix Calculator Work out how much two-stroke oil to add to your petrol at a 1:50, 1:40 or other ratio, in millilitres, with the total mix and a table of ratios. Tyre Size Comparison Calculator Compare two tyre sizes such as 205/55 R16 and 225/45 R17: overall diameter, revolutions per km and how far the speedometer will read off at 50, 90 and 120 km/h. Wheel Offset Calculator Work out a wheel's offset (ET) in millimetres from its rim width and backspacing, with the distance from the hub face to the centre line and the outer rim edge.

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