To start the car smoothly with the clutch, depending on speed its best to start in the higher gear so that engine revs won't soar too high when coming back alive again. Fuel economy pros use this technique to turn off their engine then putting the shifter into Neutral when acceleration is not needed, and then when a lower speed has been reached (say 30 mph or 50km/h) then one would attempt to restart the car with the clutch in 5th gear, since this method is much less harsh than turning on the engine with the key. One would have the clutch disengaged (clutch pedal in) and then from Neutral slide it into 5th. Then as you let rengage the clutch (slowly releasing to the friction point) you will feel it gripping the engine. Immediately let off the clutch pedal till the engine starts firing its cylinders and then right away press the clutch again to avoid aftershock. If done correctly within the second, the clutch should absorb any NVH (noise, vibration, harshness) and engine revs should rise to about 1100 rpms. If engine fails to start try a lower gear, but remember the lower the gear, the more clutch you need to absorb the greater aftershock. Engine revs could be higher during a bump start like 1500 rpms or 2000 although you want to keep these revs as low as possible in order to reduce wear and tear on the engine (rev too low and the engine won't come back on, one must know which gear to start with so that NVH is controllable for all speeds... in this case its harder to control as your momentum decreases). As the revs fall and settle to idle, one should rev match into the appropiate gear and then accelerate their way to desired speed (usualy 40mph or 70km/h before areodynamic losses are prevalant) and then repeat for maximum fuel economy. I suggest refining this technique before attempting to use in real world driving situations as if fallen to the wrong hands can be deadly (like speeding). A master with this technique can recall the engine within half a second and start accelerating as soon as that second is done with no NVH to either the driver or the passengers. And the mileage increases are reported to beat EPA highway estimates in the CITY. If one hasn't noticed why not just coast in Neutral? Simply because as your momentum decreases, the same amount of fuel used to keep the engine running won't be worth it as opposed to coasting with the engine off and mileage is still increased even at very low speeds. There is no payback for fuel coasting with the engine off as opposed to coasting with the engine on in Neutral. In Neutral one has to be travelling at higher speeds to gain the mileage benifits of coasting (since when one is in gear, engine braking prevents the car from travelling far with just momentum), but with the engine off that rule is broken and mileage soars upward at any speeds. Its just a matter of learning how to turn on one's engine when they need it the most as well as maintaining safety, passenger comfort and not overdraining your 12 volt battery.