I hope this hasn't been done before... I apologize if it has and I will delete the thread if it has...


I want to know if you use the same amount of gas when you apply medium pressure to the gas to get started to get up to road speed relatively quickly to keep traffic flow (I mean getting up to roadspeed within a city block), or someone who hardly touches the gas and takes well over a city block to get to road speed.

I know it may sound simple but the latest bull from our provincial insurance corporation says someone who takes more than a block to get to roadspeed uses LESS gas. But to me the amount of gas used must be the same, because it's not like you're stepping full on the gas to screech out, you're just applying enough gas to get to the road speed which to me would stop a lot more emissions in the air because of lessening traffic jams. IE. if you placed medium pressure to get to road speed, you would get more people thru a stop light, than by the other method, therefore lessening the amount of time overall the cars spend on the road, and therefore lessening emissions.

You theory could possibly be true, even though when you go slower you use less energy your engine will be in a very ineficient zone.

While the engine may not be operating in its most efficient range, that is only one part of the drive train.

You still have the tranie, wheels, road and air resistance that all factor into fuel use.

Your insurance provider is correct. Air resistance is a product of the square of the velocity. Plus slower acceleration does not require as much engine power and torque to get the car moving to the speed.

In the end, it all works out to lower acceleration uses less gas.

Thanks for your opinions, I very much appreciate it.

I just wonder if the real difference is that noticeable or very trivial really. I too worry about the emissions for the cars on the road sitting and waiting when people go so slow that only say 2-3 cars get thru a stop light, when at ordinary speed 6-7 would.... =)

WV, the speed of the vehicle is irrelevent; the question is about the acceleration rate and the effect that it has on the fuel efficiency of the vehicle.

When the load on an engine is low, the fuel isn't being converted to usable energy as efficiently as it is when at high load. This article explains it in more detail:

http://www.autospeed.com/cms/A_110216/article.html

Hybrids effectively avoid the low throttle/poor fuel usage problem by using the electric motor for low demand accel and by recharging the battery when the engine is running to increase the load on the engine and thereby increase the efficiency of the energy conversion. That results in better fuel economy. The difference can be fairly significant depending on conditions; 25% or more improvement in fuel efficiency is quite possible with the correct driving techniques.

Your insurance provider is wrong, and you are correct about the effect of slow acceleration on traffic flow.