Why aren't hybrids diesel rather than petrol?

[Draigflag]

I'm sure they make sense to a lot of people, it's just the cost. I guess I had it in my mind that a hybrids purpose was to save fuel money, and it does now and again for the odd short trip. Truth is, a modern diesel would cost far less to buy and run overall and there's no battery replacement worries for the future. I did want to buy a small fully electric car just to whizz around town and get to work in. But as you have to rent the battery, at £45 a month minimum, the cost per mile would be double, if not triple that of my current car.

[sealiedog]

Compared to similar sized vehicles they save fuel on almost every trip. Mine cost exactly the same to buy as the equivalent diesel powered model.
There are a few models where you can lease the battery if you want, but that's an option to bring the cost down, you don't have to do it.

There's a Tesla all electric saloon car that has a 300+ mile range and can use a super fast charger that give you 170 miles in 30 minutes. Very expensive just now, but the technology is clearly there and will get cheaper.

It does 0 to 62 in 4.4 seconds too!

[Draigflag]

Just remembered another diesel hybrid Ben, the new Range Rover. In the review it got 40 MPG on the motorway, and 36 MPG on normal roads. Full test here: Range Rover Sport Hybrid GREEN CAR REVIEW - GreenCarGuide.co.uk

[benlovesgoddess]

I love diesels, but i can't get that light metallic green mk1 insight out of my head...!

[trollbait]

Renault was doing a battery lease only with their BEVs. This allowed the purchase price for the car to be the same or lower than the equivalent liquid fueled car. Until recently, it was the only way to buy one of their BEVs, but it raises issues. How is the battery lease handled when the car is sold used? How does insurance work in conjunction on a car that is owned with a major component leased? Etc.

This actually lead to slower BEV sales. So they now have a purchase option for the battery. No Renaults at all here in the States (I'd like to see the Twizzy), but the Smart ED has a battery lease option here. It lowers the price, which really isn't an issue for the car, and includes a more robust warranty with annual testing on the battery. I'd say it is more to assuage battery replacement jitters for first time plug in buyers.

A replacement battery for a Leaf runs about $4000 to $5000, which is about how much one for the 2005 Prius cost back when I had it. The Leaf pack is ten to twenty times larger than that Prius one. Nissan and others are willing to take some loss on replacing a plugin pack in order to insure they get their hands on the bad one for study, and more importantly, for positive PR for the new market segment.

The prices are dropping on new batteries. When Tesla's Gigafactory goes live, they will be making Li-ion ones for $200 a kWh. When the Leaf first came to market, the price may have been around $700 a kWh, and it is likely around $500 a kWh now. Replacement packs should be cheaper, because it is rare that the entire pack is bad. They are made up of a hundred plus cells arranged in stacks. One bad cell will make the entire stack bad to the car's computer. Small businesses are popping up here that hunt down the bad cell in a 'dead' pack, and replace them for a fraction of a new pack's cost.

There are several ways of defining a hybrid system. One is whether it is an 'add on' to the tradtional drivetrain or if it replaces the traditional transmission. Honda's IMA was an add on, and the first or so of the mkI Insight were manual transmission only. CVTs were then used because Americans, and maybe Japanese, prefer automatics, and because the problems they had with bad battery management were made worse with a manual that allowed the driver to 'lug' the battery. Hyundai's and VW's system are another two that are add on.

The new two motor system in the Accord, Toyota's, Ford's, and GM's Voltec systems replace the transmission. They are called eCVT because they behave like a CVT when driven. Ford and Toyota systems contain a single planetary gear that has a motor and the ICE inputing to it. The computer controls to torque from each to simulate 'variable gears', but it is as mechanically complicated as a single speed manual with no clutch. The GM is similar to that with some clutch packs to allow a physical disconnect between the wheels and ICE for the EV mode.

The Accord system is even simpler, so it should be even more reliable than an automatic and manual. There is a clutch to disconnect the wheels and ICE, because it runs as a serial hybrid at low and medium speeds, like a locomotive. The conversion losses become too great at highway speeds. The ICE clutches in then, and there is maybe three physical gears between it and the output shaft to the wheels.


In short, hybrids with an eCVT don't have a traditional transmissions at all; the hybrid system is the transmission. They have far fewer parts than the traditional transmission that can fail. Even if it were possible, manual control of them would reduce efficiency, since a human couldn't control them as well as the electronics.

In theory, the CVT is the most efficient transmission for an ICE, simply because it can keep the engine at its most efficient load and rpm for the entire time it is accelerating. Some have a torque converter with its lossiness though. Then people are just used shifts on a car, so they don't like CVTs, at least in the US. So the car makers program virtual gears into some of their CVTs. Which makes no sense, and defeats the purpose.

The AC motors used in BEVs and PHVs with a full EV mode are efficient over a wide range of their rpm curve. SO they don't need multi speed gear boxes for acceleration or efficiency. DC motors aren't though. These were commonly used in BEV conversions, and were just hooked up to a car's manual transmission. This allowed a smaller and cheaper motor. It is possible a future econo BEV would use a DC motor for cost reasons, and then it might have a two or three speed gear box Continental has a design or two for them. They are automatic, but far simpler and more efficient than an ICE automatic.

[Draigflag]

The trouble with fully electric cars is the huge depreciation, I guess they don't appeal as much as a conventional car, or a hybrid. I've seen a few Twizzys for sale for just £3495 now, and the large Renault fluence for just £5000 with just a few thousand miles on the clock. When you consider how much the battery is worth, or would cost to replace, it almost makes a fully electric car obsolete V's a hybrid or conventional car.

[benlovesgoddess]

Thanks trollbait, that is a great piece of writing, very informative

[trollbait]

First, i wouldn't go by Renault BEV prices on used ones. The entire battery available for lease only has made a real mess there. How much would you be willing to pay for a used car if the ICE wasn't included, but had to be leased directly from the manufacture as the only option.

Many places where plugins are available have some type of incentive. That is going to have a negative impact on the used car prices.

The only negative story on plugin battery life has been with Leafs in the high heat of Arizona. But then the cars haven't been out for a full decade yet, so battery life is still a concern for many. The Prius will have been out for twenty years soon, and people still talk about being worried about its battery life.

The battery technology has been steadily improving, which has lead to steadily increasing performance and decreasing prices for the car. The second generation Volt's starting MSRP is something like $1,165 less than the outgoing model's, which has already received a $5,000 price cut, and maybe more, since its initial debut. So they have some of that high tech depreciation.

On top of that, gas is cheap. Back when the price spiked above $4/gallon, used hybrids were going for more than new ones. When it goes back up, so will these cars' used values.

[sealiedog]

I think the situation is rather different in Europe. The current petrol price in the UK for a US size gallon is about £4.50, which is roughly 7 dollars at todays exchange rate. And thats considered to be quite low compared to the trends of the last few years. Diesel is more expensive than that. Part of the reason they sold a lot of them in 2014.

[Draigflag]

It's actually £5.31 average across the UK, which is almost $8. I don't know if you've noticed, but there is currently a 1p difference between petrol and diesel at the minute, must be the smallest difference in decades. At least that's the case localy.

Edit, sorry my price was for UK gallon.