What is the most efficient DRIVING SPEED? I have a Toyota Aygo ( and a Citroen Xsara Picasso)

[thegreenster]

What is the most efficient DRIVING SPEED?
I have a new Toyota Aygo...
(we also have a family-sized car Citroen Xsara Picasso)
Is it different for different cars? I always thought it was 57?
In my first long drive in the Aygo felt more comfortable nearer 53-ish?
In my Picasso i feel best at about 58-60? Unscientific 'feelings'
Is there a definitive answer??

[bowtieguy]

every vehicle is different. as a general rule, the lowest speed in top gear is a good start. i've owned several GM cars w/ V6s. on those cars, when overdrive is achieved @ near 50mph, the rpms drop to1500. it's amazing that a 3500lb car can get 30+mpg on the hwy.

cars w/ auto tranny, the best idea is to stay in TC(torque converter) lock-up mode. in top gear, under TC lock-up, you can maximize fuel economy.

don't forget about DFCO(decleration fuel cut off). most drivers do not realize that when decelerating(instead of braking hard at the last moment), most modern vehicles USE ZERO FUEL(down to 1k rpm). this can be a huge benefit in your overall mpg avg.

[udtrev]

I've found for best efficiency get into top @ 40 mph, cruise around 55-60 and where possible keep your foot off the accelerator. with this method I am regularly turning in 56+ mpg with my Panda :-)

[bates]

Every vehicle is different and unique. You have to either use a scan gauge to dial it in or play with it by driving long distances at steady speeds and calculating your mileage for each different speed. Generally speaking your vehicle will be most efficent at a relatively low speed in high gear and your mpg will drop off fairly rapidly as speed increases. This is due to wind resistance increasing with the square of speed so a small increase in speed equals a large increase in wind resistance.

When gas prices were through the roof last July and LA traffic dropped down to about 50 MPH on the freeways so that all the commuters could afford thier commutes, I was getting up to 35 MPG even with 10% ethanol which hurts my mileage significantly. Now with my average speed around 65 I tend to get around 32-33 so 2-3 MPG drop to achieve a 15 MPH increase in speed on one direction of my commute (my drive home is in nearly gridlock traffic every day so while it takes forever, the mileage numbers are pretty good due to an average speed of about 35 MPH.)

Anyway, either buy a scan gauge or experiment and see what you come up with, but my money will be on your mileage being the best at the lowest possible speed, due to physics. Good luck.

[HANSN484]

My car seems to like 55-65 on the highways.

I'm not sure speed is the issue, so much as engine revving.

Lots of stop and gos aren't good for mpg. If you can roll through a stop light rather than stopping on red and going on green, merely slow down sooner, and hopefully it will turn green before you have to full stop.

I think that's helped my mpgs a ton(5-7 mpgs improvement since I've been doing it)

-Nate

[Draigflag]

Cruising at 40 MPH i got 82 MPG in my old car but 40 MPH could annoy some people, 56 is a good speed. I would reccomend being in 5th or 6th gear at 30 MPH in a smallish car and/or change gear at 1500 in a turbo or a diesel, and 2000 RPM for a normal petrol.

[jhu]

To OP, what kind of transmission do you have? If you have an automatic, the slower you are able to go in the highest gear with torque converter lockup, the better your gas mileage. On the highway, usually the lowest people can generally tolerate is about 55 mph (if you have nerves of steel, you can go lower, or if you don't you go faster).

If you have a manual, generally pulse and glide works better than constant speed.

[techathy]

Typically found that the Panda used to like about 2300rpm in any gear, where it got a nice torque spike, great for 50mph limits but was dangerously slow on dual carriage ways (if lorries want to over take you, you're driving dangerously!). The other rpm the engine liked to be around was the 3300 maker, a bit under 70mph, at that rpm the throttle input to keep the speed up hill was small, meaning the ECU didn't drop to open loop mode (meaning the ECU is primed for acceleration & runs the ARF rich rather than slightly lean, reduced fuel economy), while keeping the injector duty cycle low (low duty cycle = low fuel usage).

For cruising now I've turboed the Panda I'm finding 2800~3400 rpm is optimal, the turbo is giving some boost to giving the engine load of torque, so again the ECU doesn't drop to open loop mode for gentle acceleration or inclines, but it's not positive pressure so the injectors aren't being pushed hard. I've been finding that driving in 3rd rather than 5th at 30mph is giving an almost identical fuel usage but I have power to dart across the road without being T-boned by the guy coming the opposite way when someone starts crossing the road without looking.

With the techniques above I'm getting economy results to similar to book economy for the car, which is producing far more power & torque.