Why no motorway gear?
Discussion
Maybe there's a simple answer to this, hoping someone can answer this..
I was on the motorway on Friday night and started thinking about the 6th gear in my car. Every car I've had up until this car has had 5 gears, which have been fine and I've never felt that any more were needed.
So, why do cars not have a specific gear for motorways? for improved fuel economy
1-5 for normal driving and 6th gear designed for motorways (say 60mph+) where the car will be ticking over at 1,000rpm.
I was on the motorway on Friday night and started thinking about the 6th gear in my car. Every car I've had up until this car has had 5 gears, which have been fine and I've never felt that any more were needed.
So, why do cars not have a specific gear for motorways? for improved fuel economy
1-5 for normal driving and 6th gear designed for motorways (say 60mph+) where the car will be ticking over at 1,000rpm.
The gear ratios of cars sold in the EU will be optimised for the EU combined test cycle which looks like this:
As you can see, cars are only doing above 80kph for a very small proportion of the test, so manufacturers don't tend to gear for it.
You wouldn't want the revs to be that low anyway - optimal efficiency is not at idle revs.
As you can see, cars are only doing above 80kph for a very small proportion of the test, so manufacturers don't tend to gear for it.
You wouldn't want the revs to be that low anyway - optimal efficiency is not at idle revs.
With modern small capacity turbo engines becoming more popular, we are starting to see some very long top gears appearing. I read a review of the Audi A3 1.4 TFSi and Merc CLA 1.6, and both were quoted as spinning at just 2000rpm at 70mph. Only heard of V8's and diesels having such a long gear previously.
I did wonder the same although I was thinking more like 2000-2500 RPM. At 70MPH in 5th gear on my Focus (just a boggo 1.8) I'm at 3500 RPM.
When at 40 I could be in 3rd at approx 3500 RPM or 4th at 2500 RPM. It is a lot more fuel efficient (20% or more) to be in 4th, so I don't see why this wouldn't be true at the higher speed also.
I can only imagine it is to cut production costs and also because it would mean dropping down a gear or two every time you needed to gain a bit of speed as there simply is not enough torque lower in the range.
When at 40 I could be in 3rd at approx 3500 RPM or 4th at 2500 RPM. It is a lot more fuel efficient (20% or more) to be in 4th, so I don't see why this wouldn't be true at the higher speed also.
I can only imagine it is to cut production costs and also because it would mean dropping down a gear or two every time you needed to gain a bit of speed as there simply is not enough torque lower in the range.
In my search for a new car I've always looked out for 6 gears as I've assumed it's pretty vital for motorway trips. Then I was reminded that 6-geared cars were uncommon till recently unless it was a big diesel and then I remembered that my 60bhp punto actually cruises alright in 5th and it's only the fact it's a small car with pretty skinny tyres that it gets bashed about a bit by the wind. All my acceleration is from 3rd (normally up to 65-70mph), then I change up to 4th and get a bit of a final push up to 75-80mph and then I put it into 5th and let it cruise back down to 70mph.
It's not the best car for the motorway but I imagine something like a 1.6 focus with 5 gears is absolutely fine. Punto's are just a bit light and noisy... Not engine wise though, just wind/road noise and obviously not being able to relax in the shaky car of doom.
It's not the best car for the motorway but I imagine something like a 1.6 focus with 5 gears is absolutely fine. Punto's are just a bit light and noisy... Not engine wise though, just wind/road noise and obviously not being able to relax in the shaky car of doom.
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