[Drivingforfun]

I’ve noticed the gears in my car, along with most other cars I’ve driven, are rather close together, if that’s the correct term. You can drive in mine as high as 30mph in 1st gear (probably higher, I haven’t had the desire to stretch it harder than that) and as low as 40mph in 6th gear and the engine will be just above ticking over

Why don’t they keep the first gears close together but make top gear very “long”, such that the engine is just above tickover at motorway speeds and would stall if used at any lower speed?

This would have no real impacts on performance, no one really uses top gear when driving enthusiastically and I believe most cars can still achieve their top speed in the penultimate gear. But would greatly aid economy

Can anyone with more knowledge than me explain why this couldn’t be done, as I assume if it was that simple it would be widely adopted!!!

[Beelzebub]

The current trends are towards EVs and to automatic boxes on ICE cars. I doubt whether further development of the manual box would be on anyone's priority list.

[Santa]

@Drivingforfun

The designers choose a set of ratios to match the power/torque of the engine and a combination of attributes like acceleration, maximum speed and fuel economy. The end result is a compromise.

The closer the gears are together, the higher up the power curve the engine can stay, meaning better acceleration. Closer gears also mean better fuel economy since the engine can be kept in its optimal RPM zone for fuel consumption. However, having closer ratios either makes the highest gear too short or makes the 1st gear too long, both of which can be undesirable (see earlier). The solution is either more gears or wider ratios.

The type of transmission is usually matched to the car. Close ratios mean more shifting, so close-ratio transmissions are fitted to sportier cars. Wide-ratio transmissions tend to be fitted to cars with wider powerbands such as diesels. Formula One cars have very narrow powerbands, meaning they use very close ratios. The difference between 7th and 8th gear is only about 1.12 times, compared to about 1.25 on passenger cars.

https://www.carthrottle.com/post/nrjbm7d

[NMNeil]

I once read that a manual transmission is close to 100% efficient some of the time while an auto is 90% efficient all of the time.
Like all things automotive it's a compromise, because the manufacturer doesn't know if you live in central London where all you really need is first and second gear or out in the middle of nowhere where it's in overdrive much of the time.
Here in the US only 1.7% of new cars are sold have a manual transmission.

[Drivingforfun]

Thanks for the responses, I wasn't suggesting this would work because if all it needed was changing the size of the teeth on one of the gears for huge gains, it would probably have been done in the early 1900s!

My point is that by having a very large gap between top and second-to-top gear you still get all the benefits of having a range of lower gears, just top gear is strictly a motorway-speed gear that you know not to touch unless driving at higher speeds

I don't know if it would cost much to develop - I actually think any anti-ICE environmentalist, once they have accepted that the "nuisance" of ICE will not go away overnight - would oppose a minor change that caused them to burn less fuel while they still have to exist

I'm not an expert but I don't think being a gearbox being automatic makes this any less relevant - they would still have gears with ratios (unless it's a CVT transmission) - unless I am mistaken

[NMNeil]

Not quite 100 years ago but the addition of an overdrive unit was very popular back in the day.
https://www.hagerty.com/media/mainte...njoy-highways/