Hello fellow ecodrivers
I tested P&G, in my stock VW Up! (1,0 liters gasoline, 60 BHP), versus driving with constant speed. The average speed of all runs was 50 km/h (30 MPH).
Since my car is stock, the glides was performed with engine idling.
The pulses was from 24 MPH -> 36 MPH.
The test course was 2,2 miles of smooth tarmac, without elevation and lights, no traffic interfering and a few 30MPH bumps.
Engine warm, calm and dry weather and temperatur around 20 *C.
I havent bought a Scanguage yet, so the test was performed with the factory installed trip computer, which is shows a fuel consumption approx 5% lower than reality.
This is the measurement from my 4 runs:
1 out: Constant speed: 2,70 l/100km (87,1 MPG (us))
2 back: Pulse and glide: 2,80 l/100km (84,0 MPG (us))
3 out: Pulse and glide: 2,80 l/100km
4 back: Constant speed: 2,70 l/100km
Afterwards I wanted to calculate potential fuel saving, if I was able to turn the engine off.
By observing pulse and glide times and consumption, during the tests, I calculated theoretical P&G fuel consumptions with engine idling and engine off during the glides.
Calculated fuel consumption with P&G with engine idling: 2,89 l/100km
Calculated fuel consumption with P&G with engine off: 2,11 l/100km
The result: P&G in the test showed an increased fuel consumption 3-4% compared to driving with constant speed.
If I was able to turn off the engine of during P&G, I would certainly get lower fuel consumption.
From my guesstimations it would result in a 20-30 % decrease in fuel consumption compared to constant speed.