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Comment by Swizec | Hacker News Reader

There was a fun segment on this in an old Top Gear. A race to see how far you can get on a single tank of gas.

Clarkson thought the challenge was dumb and picked a big comfy car with a massive engine. He might not win but at least he’s gonna enjoy himself.

Ended up winning. The massively overpowered engine was chilling at highway speeds so much it barely used any gas.

Another fun comparison was when they took a Prius and a M5. When the M5 was chilling at a slightly fun speed, the Prius was struggling so hard that it had double the fuel consumption of the M5.

Cruising speed matters.

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A single tank of gas: isn't that then mostly a matter of the size of the tank? My friend with his Jeep can go very far, no issues, but filling the tank costs an arm, a leg and a kidney. Gas consumption is horrible, it just has a huge tank.

That said hybrid systems are basically KERS: they matter when slowing down (charging the battery instead of warming up brakes), and at very low to low speeds (better efficiency of the electric engine compared to a gasoline engine). I would not expect a trip on the highway without traffic to be better at all with a hybrid car than with a gasoline car.

But, within Europe, most of the driving is done under 50km/h and within the cities, where hybrids shine.

I agree that hybrids are a stupid solution, a full EV is way to go, but, for example, there are only two superchargers for Tesla in whole Berlin, which has almost 4 million population. The infrastructure has to be improved and the batteries needs to get larger or more efficient, because I find stopping every 2hrs to charge your car for 30 minutes stupid.

Hybrids are just a band-aid solution until we have proper (and cheap) EVs.

Fast charging is not really needed in cities where daily driving distances comfortably fit into almost all EV-s ranges. What is needed is parking space in residential areas with access to Type2 charging.

Access to a parking space with charging, any kind of charging, is the reason I don't own an EV yet. Japan is really lagging behind here: the building I live in was finished in March 2020, it's not even one year old, and there's no way to charge an EV car in the parking spots!

> I would not expect a trip on the highway without traffic to be better at all with a hybrid car than with a gasoline car.

Hybrid systems allow the gas engine to (essentially) always run at its ideal speed if it is running at all, storing extra energy when less is needed and drawing power from the battery when more is needed. On an idealized highway drive, with cruising speed at exactly the pure gas car engine’s ideal speed, with no variations due to turns, hills, traffic, etc., this is no benefit, but real highway driving tends to differ from this ideal enough that hybrid cars have benefits even in freeway driving.

This is true of a second-generation hybrid, like the BMW i3 (with range extender). A first-gen hybrid, which is most hybrids (including the Infiniti QX60, the BMW 3-series (not i), the Mercedes E-class) still power the wheels primarily with the gas engine, and only use the electric engine in certain reduced circumstances. With the gas engine directly driving the wheels, you don't get a lot of benefit from the hybrid except in start-stop conditions.

The first-gen/second-gen language is a bit odd. More common would be “mild” vs. “full” hybrid, but most hybrid cars sold, in the US at least, are full hybrids (what you call “second-generation” hybrids); Toyota Prius nameplates alone account for almost half of all hybrids that have been sold in the US, and all of those are full hybrids.) It may be that mild hybrids dominate if you are counting individual models, but certainly not if you are counting vehicles.

While cruising speed matters, the reason manufacturers of "economical" cars, like the Prius in your example, optimise for lower speeds is because that's where the vast majority of your time will be spent.

Top Gear's challenges were very entertaining, but they were very far from being scientifically meaningful in any way.

You’re right. Different cars are designed for different places. You want a small efficient car in the city, and a comfy cruising car on the highway.

I’ve driven both types on their home turf and in the wrong environment and it makes a huge difference.

The only truly bad type of car is an SUV. Bad everywhere.

My Ford Expedition is perfect for hauling a trailer, my family and our dogs. It has third row seating so my three kids aren’t all squished on one bench while the second heater/blower in the back is an absolute godsend when it’s -25F, as is the 4x4 when (not if) I get stuck

> hauling a trailer, my family and our dogs

vs. how often are you driving alone in that monster truck?

It’s about 50/50

Was the challenge done with a single tank of gas or a specific amount of gas? I'm guessing a car with a massive engine has a much larger tank.

Top Gear is entertainment and not car journalism. It's scary to see how people take it seriously.

I wouldn’t take environmental advice from top gear. I seriously doubt the accuracy of this

The original poster is slightly mis-remembering the episodes in question. In the first scenario much of it was down to the big car having a really big gas tank and thus going further on a single tank of gas than the smaller, more economical, cars.

In the second case they where driving the Prius around a race track as fast as they could make it go (ie nothing like cruising on normal roads) while with the M5 following at the same pace. And in those conditions the M5 did use less gas, but I don't recall it being half as much.

Did the M5 happen to follow in the slipstream? That basically nullifies energy demand at high speed...

This kind of test is mostly for showmanship. There's even a chance that an M5 will get better fuel consumption than a Prius due to the way the test was designed: making the Prius run at the absolute limit in circumstances that cannot be replicated in any reasonably legal setup on a public road, like racing. Even when "cruising" at top speed the Prius should be more efficient than the M5 at the same speed.

An M5 won't have better fuel consumption than a "normal" small car in any situation that you could reasonably see on the road.

I agree. It's automotive themed entertainment. While not totally scripted they have a plot picked out.

But you're among an online community that thinks the Hilux episode was a scientifically controlled experiment so that's gonna be an uphill battle.

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