Driving slower saves gas?

[freakyj92]

A coworker made a comment saying she doesnt drive past 70 anymore to save gas. Does driving slower really use less gas even if the you're on the freeway and speed is generally constant?

 

[olds]

Are you kidding?

 

[rsd]

I hear walking saves even more!!

 

[manlymatt83]

Originally posted by: oldsmoboat
Are you kidding?

^ what he said

 

[Scouzer]

80km/h - 40-45mpg
110km/h - 34-36mpg

Pontiac G5 GT

 

[CptCrunch]

c'mon, you must be joking

 

[bignateyk]

Depends on the car, but most reach there peak mileage around 55-60mph. That said, I drive closer to 80 on the freeway.

 

[Xavier434]

It most certainly does. What your coworker is doing is become quite common too. It also helps to let go of the gas earlier when approaching red lights.

 

[Genx87]

Of course driving slower saves gas. But there is always a sweet spot. For me it appears to be ~65 mph where I can get around reasonably fast and still get 28-30 mpg in my 2001 A4.
70 and my mileage drops to 24-25.

 

[summit]

yes, because the higher the speed even if you are in the highest gear is causing you to have a higher rpm which means you are burning more gas.

 

[OdiN]

It's not necessarily how fast you're going. It's more the RPM's, vs. speed. The optimal speed would be where RPM's aren't high, but you're still travelling fast, as in 65MPH. As you go faster, your RPM's will be higher and you will use more gas - your engine is working harder to maintain the higher speed.

So going 90MPH @ 3K RPM may get you there quicker, but you will use less gas when travelling at 70MPH @ 2K RPM or whatever.

There's other factors such as tire pressure, wind resistance, etc. But that's a simplistic look at it.

 

[Gothgar]

fuck that shit, time is money.

 

[freakyj92]

Really.... the freeways i take to and from work are always open to where i can drive as fast as i want. I always drive with the cruise control because of it... its really that big of a difference on gas if i lower the cruise control?

 

[Auggie]

It's not a gas-rate issue, Summit - it's the fact that wind resistance geometrically increases as speed linearly increases.

The efficiency of an engine is nearly the same at 40mph or 80mph. The force of the wind resistance is incredibly different.

 

[tasmanian]

Originally posted by: Summit
yes, because the higher the speed even if you are in the highest gear is causing you to have a higher rpm which means you are burning more gas.

I dont think its that. I think its that there is alot more wind so your car has to work harder. At 5th gear going 60-70ish my rpm is around 3000. While 50 they are alot higher.

 

[broon]

My durango gets better gas mileage going 80 than it does going 55-75.

 

[jjanders]

Originally posted by: broon
My durango gets better gas mileage going 80 than it does going 55-75.

Uh huh.

 

[spidey07]

Depends on the car and gearing. In a TL I get better gas mileage at 85-90 than I do at 70. 31/32 at 85 vs. 27-28 at 70.

 

[JDub02]

I normally got about 26-27 mpg on trips w/ my Mazda6. The last one I took a little slower (~65-70) and got 31 mpg for the trip. Definitely makes a difference. My car could use a tall 6th gear. 70 mph in 5th has the motor turning a little over 3k RPM.

 

[Riverhound777]

Does going downhill get better mileage than going uphill? I heard that somewhere...


/sarcasm.

 

[Billb2]

Set the cruse on 55, and be surprised.

 

[lozina]

Originally posted by: Billb2
Set the cruse on 55, and be surprised.

cruise sucks ass

it causes you to brake on downhills and rev the RPMS up on uphills

 

[PhaZe]

you have practice hypermiling

http://www.cnn.com/video/#/vid...obrien.hypermiling.cnn

http://www.hypermiling.com/

 

[Drako]

Originally posted by: Billb2
Set the cruse on 55, and be surprised.

Yep, you'll be suprised how many rude looks and fingers you get .

 

[ondarkness]

I try to keep a 60-65 average on my IS300, anything above that and the gas seems to just burn away-