Q: Does accelerating and coasting give better fuel economy than just constant cruising?
A: Don’t answer that question.
- What speeds are you operating between and acceleration rate do you use to increase your speed?
- What car are you driving, is it manual or automatic, and what is the speed limit (i.e. what constant speed would you otherwise be cruising at)?
- Is it a hybrid, does it have direct injection, or anything else that might make it more efficient than the “average” car?
The best general advice I have, for those of you who have no problem driving like a wacko, is to accelerate slowly, coast for a long time, and drive at or even below the speed limit! Just please don’t drive in front of me.
The one equation I will give is F = aV^2 + bV + c. The total drag force opposing your car looks pretty much like a speed quadratic equation. The lower your average speed is, the better. Right?
There are TWO factors in fuel economy.
- The net required energy at the wheels. This is due to the drag force, inclines, and possibly regenerative braking if you have a hybrid. 2. The efficiency from the fuel tank (or battery) to the wheels. This is due to fuel losses, heat losses in the engine and transmission, and extra loads like air conditioning and sub-woofers.
The best answer for those who are still reading is to hook your Android smart phone up to your vehicle’s information network (CAN) through the handy OBD-II port under your dash. I found a free Garmin app and for $90 I bought a wireless OBD-II to Bluetooth transmitter so I can read and record live data, AND check codes!