Driving slower saves gas?

[0roo0roo]

Originally posted by: spidey07

Originally posted by: SparkyJJO
about 50 is good for many cars. Keeping the RPMs lower in the highest gear possible is a good way to save gas.

That is simply NOT true. My car LUGS at 50 in top gear and gets terrible gas mileage. That's why I get better gas mileage at 85-90.

For example a corvette gets it's best mileage at higher speed as well. You can't make blanket statements because it all depends on the motor and the gearing.

so whats this bizarre car you drive?

it would have to be seriously poorly designed if it gets better mileage at 90 than 50. i would say botched engineering is the only way that would be possible.

 

[Eli]

Originally posted by: 91TTZ

Originally posted by: Eli
Driving my Insight has taught me a lot about fuel economy.

I get the best fuel economy in town using the 1-2-5 shift method. And I floor it.

1st - floored to ~3,000RPM, shift, floor 2nd to desired speed, shift into 5th.

Originally posted by: gnumantsc
I tend to accelerate really slowly making sure I don't go past 2000rpms from a dead stop. I see all these other cars zoom by or try to make me go faster when the light is red. I don't give a crap that the light is red and you want me to waste my gas?

When going on a long trip I would rather drive faster than to save gas if its an hour difference that's a big difference in time but for say going to work an extra 5 minutes is no big deal.

I've found that accelerating slowly does me no favors. It's a time vs. instant mpg thing. I wonder if I could gather enough data to actually run the numbers.

When accelerating, the Insight engine uses a lot more fuel than it normally does. If it takes me say, a minute to get to my desired speed, I might only be getting 35MPG during that time.

However, if I employ the 1-2-5 shift, I will only be getting 20MPG while accelerating hard, but thats only the first 20 seconds or so of the minute. Now that I'm up to speed, I can shift into 5th, lean burn will kick in and I will get 65+MPG for the remainder of the minute.

There is no way that you'll get optimum fuel economy by flooring it.

Also, the previous poster who stays below 2000 rpm is most likely revving his engine well below the point of peak efficiency. An engine is most efficient at the RPM that it produces peak torque.

I do though! But my car isn't the norm. Still, it would be interesting to watch the instant MPG gauge in a non-hybrid car and compare.

Think about it. If I floor it, I get full electric assist and my instant MPG drops to 20-25MPG.

If I shift through the gears and keep the RPMs low, yes, my instant MPG is higher, but it's also taking me longer to reach my desired speed, and its still low, about 35MPG.

This is especially true if you are starting on any sort of incline. If I'm starting on a noticeable decline, I may only floor it through 1st, if at all.

What really kills my MPG are long, fairly steep inclines. The car really has no power without the electric assist, and unless I want to deplete my hybrid battery, I have to shift into 3rd.