[safgasCVS]

ICE motors have been evolving for over a century now so the improvements will become ever smaller. Despite that slowdown in progress, the energy density advantage of fuel over batteries still vast. Regulation should, in my opinion, be be aggressively pushing towards reducing vehicle size and weight instead of focusing on the fuel. Having a 2 ton car to move a 60kg person from stop light to stop light is just insane

[avhon1]

One of my personal fantasies is that the United States imposes a maximum road speed limit of 45 miles per hour (72 kilometers / hour). As a result, cars get lighter, more efficient, and safer, and trains become more popular and practical means of traveling long distances.

45 miles an hour seems like a reasonable compromise speed. At 65% the common highway speed limit of 70 mph, it's still fast enough to cross most states in a day, to travel between nearby cities in an hour or so, and to do errands in an afternoon. But a car at that speed has only 41% the kinetic energy as at 70 mph, making colisons less lethal, and has similarly less wind resistance, requiring smaller engines and less fuel.

Maybe I just think trains are romantic...

[clarry]

I'm conflicted on this because I'd like those gains in safety and efficiency. I think it'd also allow us to live with smaller & curvier roads, which I think are romantic and kinda relaxing. (I'm quite bored with the wide straight flats they build; those also ruin the scenery and generate lots of noise)

On the other hand, cars have been getting safer and faster and more efficient, roads have been getting wider and safer.. only speed limits haven't been lifted to match. A part of me wants to live the utopia where I can get where I want to be in less than half the time it takes today. That'd make the difference between going to my parents for a coffee after work vs having to reserve a full day (if not a full weekend) for the trip.

Trains are not really a solution around here.

[avhon1]

I think speed limits have informally (and unevenly) been rising to match the capabilities of new cars and roads. I visited a new area recently, and was shocked to see that traffic was flowing at 90 mph (!) in a 70 mph zone.

I was glad I wasn't driving, because not only is that a greater posted-vs-actual speed difference than I've seen before, but I've never actually driven that fast in my life. I'd have been torn between driving 80 in the right lane and being constantly passed at 10-15mph, or being white-knuckled behind some other vehicle and setting a personal landspeed record.

[throwaway0a5e]

Safe traffic speed is a tautology since (at least per current civil engineering doctrine) speed limits are based on the Xth percentile (where X is usually somewhere in the 75-90 range).

Speed limits themselves only have a passing correlation to safe traffic speed. Almost nobody actually follows them intentionally at scale (traffic just moves at the maximum safe speed which just sometimes happens to be at or below the posted limit) which is why most municipalities are abandoning the "slap a sign with a low number on it" approach for "traffic calming" road features. Traffic moves at what it considered to be the highest safe speed for the conditions (a bunch of factors too long to list). You're seeing high differences because there's many roads that have speed limits that are unrealistically low for light traffic conditions (often below the designed speed of the road) and traffic density (as opposed to visibly or a sharp curve) was the road condition that was the bottleneck on speed on most busy roads. 'Rona has widened that bottleneck so of course you're seeing bigger differences between the posted limits and the traffic speed on those roads (which is probably all roads if you only ever drive during daytime hours in urban areas).

Edit: kind of got off on a tangent there but the point I should have made is that speed limits are fixed whereas traffic speed is variable based on conditions. As conditions change both slowly over time and day to day/hour to hour the max safe traffic speed changes. With 'Rona chopping congestion across the board it's no surprise that you see traffic speeds much farther from the speed limit on roads where traffic volume was a big factor in the traffic speed.

[clarry]

Maybe they have in some areas.

In my case, rural Finland, it's been the same for as long as I remember. Maximum limit is 120 km/h on freeways (and there are practically none of them where I usually drive), elsewhere on bigger inter-city roads it's 100 km/h during summer and 80 km/h during winter. Lesser roads, never more than 80 km/h.

And traffic never flows significantly faster than the limit. A few km/h over the limit at most. There are some weirdos who drive much faster and are constantly overtaking others, but relatively few people drive like that. If anything, it seems to me that speeding has become less common over the years as the police have tightened the limit at which they'll fine you.

[TomMarius]

I am from the Czech Republic. Left lane on highway is informally reserved for "going fast", as in 160-200+ km/h. Right lane is around 120-140 km/h. Oficial speed limit is 130 km/h. Regional roads are limited to 90 km/h, but people travel as fast as 160 km/h on the largest ones. Town areas are limited to 50 km/h unless said otherwise and it required automated radars to get drivers to go less than 90 km/h in many towns on major roads.

People are basically behaving like it's German autobahn everywhere. Even the informal rules have adjusted - in a major city, you not only respect the right hand rule, but also give right of way to all vehicles on the more major road. The conflict is resolved by blinking headlights.

Honda used to be the most popular brand here (90's and first few years of 00's).

[jacobush]

You could just build better trains, it's going to take state or fed level money to do that anyway. If the trains were better, people would use them. In practice, todays 70 mph is not much different from 45 mph. You can't drive 70 mph nonstop, medium speed is lower.

[avhon1]

Yes, my fantasy is less like "improving Amtrack" and more like "replicate Japan's Shinkansen".

[ectospheno]

Japan is the size of California. Replicating that across all of a larger country such as the United States isn't realistic.

[0xffff2]

>You can't drive 70 mph nonstop

What do you mean by that? If you're covering long distances in the Western US, it's not at all uncommon to be driving 70+ for hours at a time.

[_ph_]

Having a 2 ton car to move a 60kg person from stop light to stop light is just insane

That is solely determined by the energy required. And there is, where the electric car excels. A Tesla uses less than the equivalent of 2l of fuel for 100km or in other units achieves 120mpg. In situations you describe, it fares even better, as 60% of the kinetic energy built up is gained back when braking using the electric motors. So mass is much less a problem with electric cars than with combustion engines, which can't recuperate the kinetic energy.

[rootusrootus]

Regenerative braking is always, always less efficient than just not spending the energy in the first place to speed up.

And there are currently more fossil fuel cars on the road with regenerative braking than there are EVs ;-)

[_ph_]

To use 60% less fuel, the car needs to havee appropriately less mass, so you are talking about 700kg for a 5 seated car with passengers. If you are talking about fossil fuel cars with regenerative breaking, you are talking about hybrids, which use their electric part for that, but their breaking power is limited compare to pure EVs by the electric engine power and the charging limits of the smaller battery.

[avhon1]

Electrics are great for low-speed stop-and-go. They're not as good on a highway, though. 0% of the energy spent displacing air at 70mph is recovered.

[_ph_]

They are still better than any car with a combustion engine at highway speeds. They don't recuperate while driving at constant speed of course, but still they have the greater efficiency of the electric motor vs. the combustion engine. Usually they have better aerodynamics too. But the weight doesn't play a role there, only making the cars physically smaller - less air resistance - would improve the energy consumption at highway speeds.

[FrojoS]

Yes, but weight (which is higher in electric cars) does not influence air resistance. Tesla’s btw have record low air resistance.

[safgasCVS]

I don’t disagree with you but I see that as an aside. Millions of people don’t need 2.5 ton SUVs to cart themselves to and from the shops. Yes ok BEV will do it better but we have had scales for longer than we’d had batteries