Hybrids and racing cars ! Technically they're the same thing now in Formula 1 and the Le Mans cars, although not quite as hybrid as the road car I have at the moment. First ... a few myths to dispel.
Myth - Hybrids are slow. Haha, not any more they're not ! As well as giving lots of mpgs, they pack quite a punch on the acceleration. My IS is a bit tubby compared to the other cars I've owned but it can go 50 to 70 when overtaking before it has got level with the car in front. The electric motor gives them quite some welly.
Numbers - the quickest car I had before was a Focus ST170 with 170bhp and 170lbsft of torque. The bhp says how fast it can go but is largely irrelevant after that. When you're going quickly, that's when the air drags the car backwards. You need a certain amount of power to maintain the speed, to balance that drag force. And that drag increases with the square of speed. Torque is the acceleration force, it's what makes the car go really quick and determines that ease of driving thing that lets you maintain a speed despite the road going up or down.
The IS300h I have now has a 180 bhp engine with 160lbsft of torque. So about even on the engine. (Actually thought it had more torque but it is set up for economy !). The motors put in 143 bhp and 220 lbsft of torque. You don't get Engine + Motor power though because they give their best at different speeds. They say 220bhp for the combined, which is plenty fast enough especially when you compare the mpgs to the old Focus (45 min compared to 26-30) and the emissions cost (£10 per year compared to I think £250).
Myth - You need to change the battery.
Nope ! There are allegedly Prius hybrid taxis going strong with almost half a million miles on the clock. How do they do this ? You know how laptop batteries die quick but mobile phone batteries last pretty well ? There are two danger points for batteries where damage can happen :
Battery too full - they heat up when you try and squeeze too many Joules (it's a unit of energy) into them, which is why phone chargers have intelligence built in that drops the charging rate when topping off. The heat is what damages the battery.
Battery empty - when this happens, the electrolyte (the chemical soup that is the bit that makes it a battery) starts dropping chemical crud onto the electrodes (the metals that take the charge from the electrolyte and send it to the bit that needs power).
Both cases steadily make the battery less efficient, to the point where you unplug that laptop and it instantly dies despite the battery claiming to be 100%.
The Toyota/Lexus hybrid system deals with this by putting a few limits on the system :
Battery limits - not too full, not too empty. The engine will come on to recharge the battery when it gets to about 20% and the system will go to the mechanical brakes when the battery gets too full. Still, hilly country can be a bit of a challenge for it.
Current limits - this is the rate at which power goes into and out of the battery. Too much and it can cause damage, so the system limits the current until everything is at the right temperatures*.
*(This isn't just a hybrid thing, that Focus ST took away maybe half the engine power while it warmed up).
That said, I don't know how the other manufacturers manage it on their cars.
You need to plug them in right ?
Depends on the car. My car doesn't have a plug. The battery recharges on soft braking and from the engine. I couldn't actually get a fully electric plug in car because I don't have a garage to hide the car in. And I definitely wouldn't recommend trailing a 13 amp lead from house to car ! Nah, I plug mine into the petrol station like most other cars :-).
They're too quiet and a hazard in car parks !
With respect, this is more about those people who don't look where they're going in car parks and blame their inattention on other things. Most modern cars are near silent these days, you hear the tyres on the road more than the engine.
They are quiet - but people in car parks really need to be using their eyes as well as their ears and the people who complain "Your car is too quiet!" were usually not paying attention.
Myth - the gearboxes are bad !
The Toyota/Lexus system is a Continually Variable Transmission (CVT). Instead of having ratios set by cogs with certain amounts of teeth, the gear ratio changes according to what you're asking the car to do. This can lead to odd things happening with the engine revs where the engine revs go high without much apparent effect in acceleration. Yeah, I see this sometimes. And then I switch into Sport mode and go ZOOM.
I actually quite like the CVTs. They use what the car has to the optimum. I thought my CT was a bit lacking in outright power but if you asked it to go, it gave you all it had. The ST would quite often bog down where it was trapped in a rev range where the engine had minimal power. The ST also suffered from a big gap between 2nd and 3rd gear too. If you ask for economy, it will make the engine spin as slowly as it can get away with for cruise mode. If you ask for speed, it'll give you everything its got.
And that goes for the conventionally powered cars which have CVTs too. Drive one, see what you think of it. Test out the throttle response, see how it reacts.
Hmm - any more myths ... I may come back to that.
I would heavily recommend hybrid cars. As long as you get one that is worth it for power (Prius Gen 3, Lexus CT) and meets that magic 10 seconds to 60 figure (for flexibility in the car, not for being a speed demon), then you get driving flexibility, low emissions (for that road tax) and can get great economy too. Wins all round. Oh and you get the novelty of hearing the engine of the car next to you at the lights and not your own. Some of the systems aren't as good though, balances of 200 bhp engine and 40bhp motor aren't useful in my opinion.
Racing cars ?
Not quite as exotic as the Formula 1 cars though. These have a couple of motors ...
Electric braking assist - MGU-K, which charges up the battery when the car brakes.
Turbo generator - MGU-H, which works with the turbo.
The MGU-H is the exciting technology, although I'm not quite sure how it would help a road car ...
What's a turbo ? An engine works best when a set ratio of air and fuel is burned together. Too much or too little of either and it doesn't run well and you can only fit so much in the cylinders. Bigger engines give more power but they're also far less efficient. But what if you can get the big engine effect from a more efficient engine ?
Enter the turbo. These work by getting more air in, compressing it down. Higher pressure means more oxygen to burn and if you put more fuel in too, your little engine works like a big one. If you take a 1 litre engine and double the pressure of the air going into it, it's the equivalent of a 2 litre engine.
It does this by spinning up a turbine that works off the engine exhaust. But there is a cost here, it takes a bit of time to spin up the turbo as the exhaust pressure builds, which can lead to unpredictable behaviour ...
The Formula 1 system eliminates that turbo lag by having a motor generator. When there is no exhaust pressure, the motor spins the turbo up so the power is instantly available. When the engine is going Fast, the turbo helps charge the battery which they use as "deployment" to boost them from 200mph to 220mph on the faster straights.
That's the exciting bit ... but the F1 people are showing that it's a really difficult system to master. They have different aims though. A road hybrid is about cruising along using the energy store to even out the drive. A race car hybrid is about max power as much as possible.
I think I've rambled on enough for today - I hope I didn't descend into engineering geekery too much ! Here's the summary :
Hybrids - the way of the future.
Battery only cars - maybe a bit of a dead end until the infrastructure catches up.
Turbo assisted hybrids - very interesting technology ...
Oh and for the curious - the power of a F1 or WEC hybrid motor assist ... is about the same as what the Toyota/Lexus motor gives. Think about that when someone says the hybrids are slow :-).
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