Hypermiling with an old BMW 523i E39 (42,8 MPG / 5,5 L/100 km)

[Silent Blood]

Hello there!

I would gladly like to share my hypermiling story with you.

To my person: I´m male, 37 years old, live in germany. I purchased an BMW 523i E39 (sedan, 5 - gear - manual) with an M52 engine (same as the US - 528i, just a little bit smaller, 2,5 unstead 2,8 litre) in the year 2005. The car was built 1997, and most the time I drove it with about 8,5-8,7 litres per 100 km (27,0-27,7 mpg).

A few years ago, I decided to figure out, how fuel saving it can be. I extend the rear axle around 16 percent, fill in 0W40 motor oil, and learnt how to drive very economic.

Result over about 10.000 miles: 7,0 l/100 km (33,9 mpg E10, 95 octane). Average speed: 34,7 mph (56 km/h), mix of highway ("autobahn"), village streets, and a small amount of coty driving. On single short roads, I sometimes reach a value about 5,5 l/100 km (42,8 mpg). For example: Last time I drove a 118 miles long road, from even hight of the location, to a even hight, maximum speed: 60 mph (97 km/h), average speed: 56 mph (91 km/h). On slight downhill I put out the gear, on stronger ones I use the fuel cut-off, by letting the gear in, and just put my feet off the gas pedal.

I think, this is very remarkable for a car like this. Remember, it´s 23 years old (was released in 1995), got a petrol straigth six engine, has only 5 gears, weighs with me inside 3594 pounds, has no electric steering, no direct injection, of course no brake energy recovering, no hybrid, no lean burning technology...The only thing, what´s advantageous on this car for fuel saving purposes, will be the aerodynamics (cw x A = 0,59 m²)

What do you think? Did anyone have a tip for further fuel saving experiments?

[ptitviet]

Hi! That's a very nice car! What I would recommend is to practise if possible on your trips pulse and glide. The more powerful the engine, the bigger improvements you will see with this technique.

It worked awesomely well with my previous Megane 3 RS (-1l/100km) and I cannot see any improvement with my present car ('15 Octavia Greenline).

[Silent Blood]

Pulse and glide meant, to step full on the gas, and then put the feet off the gas? I didn´t practice it yet at all, because I would like a ride, as smoothly as possible (that´s why I love the r6 petrol engine). 1 liter / 100 km less in comparism to what? I need values.

[cRiPpLe_rOoStEr]

Originally Posted by Silent Blood

Pulse and glide meant, to step full on the gas, and then put the feet off the gas?

IIRC that's what pulse and glide is meant to be. Never tried it.

On a sidenote, have you ever considered a transmission swap if you could actually find a 6-speed one with a broader gear spread?

[Silent Blood]

No, I don´t like 6 gears. I was working in a car rental, almost every car there with manual gearing had 6 gears. In my opinion, five gears are enough, if manual shifted. By the way: BMW offers a gear box with 5 gears, which is reaching the same spread (5,0) than the box with 6 gears. Of course, I could reach more wheel tourque with smaller "gear jumps" (I don´t know the term in english ), but I don´t care, not anymore.

My current fifth gear has similar engine rpm than a comparable BMW with 6 manual gears (523i E60 or 523i F10), but my transmission has a pretty low spread (4,2), so the first gear is a bit long. But - my clutch is still alive, after almost 110.000 miles.

Since I´ve read about the Chevy Caprice from "funkhoss", I´m pretty discouraged. His car is more fuel efficient than mine, despite bigger engine and more mass.

https://ecomodder.com/forum/showthre...mpg-33961.html

[ptitviet]

Hello! Pulse and glide would be :
- accelerating with about 80% throttle in the best efficiency area of the engine (2-3krpm)
- switching to neutral and letting the car coast until speed is too low

If not too much traffic you can for instance do it on a 20km/h span between min and max speed.

I personally find it interesting to mix it with slopes : pulsing uphill and gliding downhill

[cRiPpLe_rOoStEr]

Originally Posted by ptitviet

I personally find it interesting to mix it with slopes : pulsing uphill and gliding downhill

Once I tried neutral-coasting with the engine off in a 2004 Corolla with automatic transmission. I wouldn't want to give it another chance.

[ptitviet]

Originally Posted by cRiPpLe_rOoStEr

Once I tried neutral-coasting with the engine off in a 2004 Corolla with automatic transmission. I wouldn't want to give it another chance.

My advise was for manual gearboxes...

[GreenTDI]

What is your tire pressure? For example, there is a big difference noticable between 2.4 and 3.1 bar and it's totally free. Check the sidewall of your tires for maximum pressure and stay under it.
You could block the front grill with insulation foam or install a 'winter grill' that will also improve the airflow in the front of the car.

[cRiPpLe_rOoStEr]

Originally Posted by ptitviet

My advise was for manual gearboxes...

Sure, and on a sidenote being able to resort to the transmission and the clutch in order to provide some engine-braking while EOCing downhill might be less dangerous than what I did. Or eventually using the impulse once the downhill stretch is over to bump-start the engine on flat terrain.