Mercedes w210 e320 optimum driving speed

[BATFINK]

I'm doing motorway mileage two to three times a week and not fussed at what speed I travel during this commute so wondered what is the actual optimum speed for good fuel economy. E320 petrol.




Sent from my iPhone using Tapatalk

 

[John Jones Jr]

56mph, if you can do it!

 

[bob6600]

Best MPG's quoted by manufacturers are normally 56-60mph which is a bit slow for me unless you want to sit behind a HGV in the first lane all the way.

 

[Meldrew2]

Just follow the formula a - b = ideal speed

a = model number on boot lid
b = series number

Therefore E320 - W210 = 110 mph.

Simples!

 

[renault12ts]

My best ever, over 50 mpg, was done at a constant 50 mph.

 

[Ted]

Just follow the formula a - b = ideal speed a = model number on boot lid b = series number Therefore E320 - W210 = 110 mph. Simples!

Erm clk200-a209...??????

 

[Deleted member 113659]

Just follow the formula a - b = ideal speed

a = model number on boot lid
b = series number

Therefore E320 - W210 = 110 mph.

Simples!

Haha. Loving that equation. Made me laugh.

Ant

 

[Stratman]

Erm clk200-a209...??????

Clearly you need a bigger engine :bannana:

 

[Charles Morgan]

Just follow the formula a - b = ideal speed

a = model number on boot lid
b = series number

Therefore E320 - W210 = 110 mph.

Simples!

I'm not sure my E320 W124 is capable of 196mph.

 

[190]

60mph or 2000 RPM

 

[hotrodder]

Aerodynamic drag is the biggy as it increases with the square of speed i.e. double the speed and there's 4 times as much drag, triple the speed and it goes up 9 fold
The most economical speed varies with different cars due to different co-efficients of drag, frontal areas and also other stuff like gearing but is typically a bit faster than the lowest speed the car will pull in top gear without labouring the engine [/gross simplification]

 

[190]

...also other stuff like gearing but is typically a bit faster than the lowest speed the car will pull in top gear without labouring the engine [/gross simplification]

In other words sufficiently up the torque curve to be efficient. It's a something of a simplification but specific fuel efficiency is approximately the mirror image of the torque curve so it will be best close to peak torque and reasonably good when the engine is making say 75% of peak torque. I said simplification because efficiency also depends on engine load which is why modern cars with very high gearing are fuel efficient, not only because they are doing less revs but because higher gearing loads the engine more which requires a larger throttle opening. As an example of the modern trend my C180K with 1.6 engine is higher geared than a W210 320e.

We don't know the year but a W210 320e is geared at close to 30mph/1000 RPM which is why I said 60mph or 2000 RPM. Peak torque is at 3000 but it's making a decent amount by 2000.

 

[John Jones Jr]

Aerodynamic drag is the biggy as it increases with the square of speed i.e. double the speed and there's 4 times as much drag, triple the speed and it goes up 9 fold
The most economical speed varies with different cars due to different co-efficients of drag, frontal areas and also other stuff like gearing but is typically a bit faster than the lowest speed the car will pull in top gear without labouring the engine [/gross simplification]

Gross simplifications are great, thanks.

 

[BTB 500]

Surely if speed is really irrelevant (as per the OP) you can be at the same point on the torque curve in a lower gear, and have less aerodynamic drag ...

I know if you get too slow then the 'overheads' (frictional losses in the engine, gearbox, AC, alternator, etc.) become too significant, but the real 'most economic' speed could well be in the 30-40 mph range. The annual Shell mileage marathon requires an average speed of at least 15 mph, presumably because people could get even better figures (in specialist vehicles of course) by going even slower than that!

 

[BATFINK]

Thanks guys interesting answers especially Meldrew. Haha. 56-60mph is doable for me on the roads I'm commuting on but more than likely 60mph when I try to max fuel economy


Sent from my iPhone using Tapatalk

 

[gIzzE]

It is around 45mph on the E320, it will slip into top gear and get close to 40mpg, maybe more on the saloon, mine was an estate. Going up to 55mph it would drop to around 36mpg and 70mph would see 33mpg.