Now this may sound as totally absurd to some but I don't know how many of you performance/lap time freaks have looked past the (indeed) astonishing 0-60 times of electric cars (let's stick to Tesla for this discussion). For anyone that has, they must have certainly noticed once the launch factor is removed from the equation, EVs are much slower than cars of similar bhp and power/weight in terms of in-gear acceleration and it gets even worse as they are behind ICE cars with as little as 50% of their own nominal power in some cases (times easily available).

 

Don't get confused, I am not talking about instant, gear-less torque. People are usually amazed from (and can't look past) the fact that an EV begins accelerating instantly at any speed but take a look at the rate of this acceleration especially above 50-60 mph and it would be utterly disappointing for any ICE car with such advertised horsepower, yet not often do you see this mentioned in such discussions. 

 

Take for example one of the quickest Model S, the 690bhp Tesla Model S P85D. Its 40-100mph (hardly an out-of-this-world acceleration scenario) sprint takes around 7,5s and the 60-120mph run takes between 11.2s - 12s, (from a car that's rated as 690bhp). These figures are matched by cars like an RS3 that's almost 50% down on power and nearly most cars between 400-450bhp. Above that there is no comparison really.

 

Which finally begs the question: Drag-racing/standing start aside, why the in-gear acceleration of electric cars is not on par with (actually: it's much worse than) their ICE equivalents? Is the power delivery so different? A dyno run of a P85D suggests otherwise, power is maxed out early enough and stays there. Is it the gearing of ICE cars? Also, before you say weight, you can compare the same 2200kg P85D Tesla with previous gen E63 AMG and BMW M5 that are also just below the 2-ton mark, yet they destroy the Tesla at any sprint from 60mph above with as little as half the time it takes the P85D to go from 90 to 150mph. So there's definitely something weird about those electric horses in my eyes...

 

 

Well reasoned. I'd never looked at in-gear times for an electric car, but this makes sense given that the torque of an electric motor is inversely proportional to its rotational speed.

Like everything in this world is a compromise, so is the design of the modern electric vehicle.

 

Simply put, electric motors have an RPM sweet spot range like IC engines. They're meant to be and feel impressive 0-60 and run efficiently between that range for great everyday commuting. In theory, if you combined a gearbox with an electric motor, you could alleviate the shortcomings you mentioned in comparison to ICE cars.

 

In practice there won't be an electric car with a gearbox put into mass production due to a long list of drawbacks. It would be expensive to design and would have no buyers. Manual? Very few people looking to play with a stick in a car that expensive. Automatic? Gearboxes sap power, the marketing department would be furious, it would ruin their pamphlet. Okay, even if you would decide on putting a gearbox on your electric motor, you'd bump into the fact that nobody makes a compatible gearbox. If we leave aside the fact that putting a gearbox and drivetrain in a Tesla would cut down on its comfort (smooth acceleration whenever you press the pedal, no hesitation) and practicality (all that stuff takes space, in this application, A LOT) , then we find that the massive instantaneous torque quickly breaks even the best available ICE gearboxes and putting a huge lorry gearbox would take a lot of space and ruin the dynamics of the car. Gear changes and transmisson losses also mean a drop in 0-60.

 

Tesla tried a gearbox on their Roadster. Tried. There's good reason why the only electric cars in mass production are luxury-commuter or full blown luxury sedans. Diesel motorcycles are rare, too. For good reason.

 

To the average person, thanks to marketing a Tesla Model S is comparable or even more desirable than, let's say, a BMW M5. If you compare horsepower and 0-60 times, wow, electric cars are great. If you take one for a spin, it will feel amazing. It's the future, right? For commuting around town, sure. But around something like the Nürburgring, give me that M5 any day. They're on a completely different level there, even if a marketing pamphlet says the Model S has more horsepower and a better 0-60 time.

 

I would absolutely love to have a Model S, or even better a Model X. Would suit my needs perfectly. Lots of 0-50mph drives with almost never more than 150 miles per day. But let's not be blinded by the marketing hype, it's no sports car. People like to believe that electric cars are superior in every way, but they're only superior in commuting and showing who's the man at traffic light races.

21 minutes ago, TLV said:

Like everything in this world is a compromise, so is the design of the modern electric vehicle.

 

Simply put, electric motors have an RPM sweet spot range like IC engines. They're meant to be and feel impressive 0-60 and run efficiently between that range for great everyday commuting. In theory, if you combined a gearbox with an electric motor, you could alleviate the shortcomings you mentioned in comparison to ICE cars.

 

In practice there won't be an electric car with a gearbox put into mass production due to a long list of drawbacks. It would be expensive to design and would have no buyers. Manual? Very few people looking to play with a stick in a car that expensive. Automatic? Gearboxes sap power, the marketing department would be furious, it would ruin their pamphlet. Okay, even if you would decide on putting a gearbox on your electric motor, you'd bump into the fact that nobody makes a compatible gearbox. If we leave aside the fact that putting a gearbox and drivetrain in a Tesla would cut down on its comfort (smooth acceleration whenever you press the pedal, no hesitation) and practicality (all that stuff takes space, in this application, A LOT) , then we find that the massive instantaneous torque quickly breaks even the best available ICE gearboxes and putting a huge lorry gearbox would take a lot of space and ruin the dynamics of the car. Gear changes and transmisson losses also mean a drop in 0-60.

 

Tesla tried a gearbox on their Roadster. Tried. There's good reason why the only electric cars in mass production are luxury-commuter or full blown luxury sedans. Diesel motorcycles are rare, too. For good reason.

 

To the average person, thanks to marketing a Tesla Model S is comparable or even more desirable than, let's say, a BMW M5. If you compare horsepower and 0-60 times, wow, electric cars are great. If you take one for a spin, it will feel amazing. It's the future, right? For commuting around town, sure. But around something like the Nürburgring, give me that M5 any day. They're on a completely different level there, even if a marketing pamphlet says the Model S has more horsepower and a better 0-60 time.

 

I would absolutely love to have a Model S, or even better a Model X. Would suit my needs perfectly. Lots of 0-50mph drives with almost never more than 150 miles per day. But let's not be blinded by the marketing hype, it's no sports car. People like to believe that electric cars are superior in every way, but they're only superior in commuting and showing who's the man at traffic light races.

 

 

That last sentence >    

 

I agree with most things but before this becomes another "electric vs ICE" thread I would like to focus even more on my original question which is: Why the electric horsepower performs worse than the ICE one in the in-gear aspect? I appreciate they are very different approaches but, horsepower by definition measures the rate at which work is done: it already includes the time factor in it so similar bhp on similar weight should produce similar performance (as is the case between ICE cars and minor differences are down to gearing and power delivery), however it is clearly not the case. I can only explain it in two ways: Either the power classification of electric motors results (deliberately or not) in inflated figures, or we are using a wrong unit and should come up with something new. There is no other explanation of that huge gap in in-gear performance especially on very similar cars in terms of bhp and weight.

 

As it stands, in order to get a good idea of how well an electric car will perform in real-life acceleration scenarios (no that's not traffic lights) you should very roughly deduct 40% of its nominal horsepower and then look up how an ICE car with that (reduced) bhp performs and you will be pretty close to reality it seems. This doesn't sound right to me.

Edited 27 March, 20179 yr by newbie69

Ignore units - Power = torque * rpm.

 

For a hydrocarbon motor, torque climbs fast(ish) from idle to 2_000 rpm, then usually more or less plateaus (particularly with a turbocharged engine) until ~peak rpm - 10%.

 

For an electric motor, peak torque happens at 0 rpm, and then drops steadily.

 

So the electric motor produces less power as it spins faster. When did you ever see an electric car maker state "peak power M KW at N rpm"?

and try running an M5 on sunshine

6 hours ago, newbie69 said:

Now this may sound as totally absurd to some but I don't know how many of you performance/lap time freaks have looked past the (indeed) astonishing 0-60 times of electric cars (let's stick to Tesla for this discussion). For anyone that has, they must have certainly noticed once the launch factor is removed from the equation, EVs are much slower than cars of similar bhp and power/weight in terms of in-gear acceleration and it gets even worse as they are behind ICE cars with as little as 50% of their own nominal power in some cases (times easily available).  Don't get confused, I am not talking about instant, gear-less torque. People are usually amazed from (and can't look past) the fact that an EV  begins accelerating instantly at any speed but take a look at the rate of this acceleration especially above 50-60 mph and it would be utterly disappointing for any ICE car with such advertised horsepower, yet not often do you see this mentioned in such discussions.   Take for example one of the quickest Model S, the 690bhp Tesla Model S P85D. Its 40-100mph (hardly an out-of-this-world acceleration scenario) sprint takes around 7,5s and the 60-120mph run takes between 11.2s - 12s, (from a car that's rated as 690bhp). These figures are matched by cars like an RS3 that's almost 50% down on power and nearly most cars between 400-450bhp. Above that there is no comparison really.  Which finally begs the question: Drag-racing/standing start aside, why the in-gear acceleration of electric cars is not on par with (actually: it's much worse than) their ICE equivalents? Is the power delivery so different? A dyno run of a P85D suggests otherwise, power is maxed out early enough and stays there. Is it the gearing of ICE cars? Also, before you say weight, you can compare the same 2200kg P85D Tesla with previous gen E63 AMG and BMW M5 that are also just below the 2-ton mark, yet they destroy the Tesla at any sprint from 60mph above with as little as half the time it takes the P85D to go from 90 to 150mph. So there's definitely something weird about those electric horses in my eyes...

 

Well there was a Renault Zoe (and R40 longer range version i think) I was having a bit of fun with (I was in the similarly power Logan ie 90hp) on the M40 and I was quite impressed with the Zoe cruising at around an indicated 125 kph ie 78 mph and he was prepared to push it to 140 kph, indicated, ie 87 mph.  I think he struggled a bit on one of  the big hills but then his car weighs about quarter of a tonne more than the Logan, despite being at least two foot shorter and certainly cannot match the 175 kph/110 mph top speed of a Sandero/Logan.

 

0 to 50 mph is about 8 seconds for the Zoe but after that it does tail off and the quarter mile does take 18 seconds but it is doing 74 mph in that 400 meters/440 yards and that is more than the National speed limit and with the usual speedo error, even digital ones in the Zoe and my Clio mark 4, would probably being showing almost 80 mph, faster enough for UK roads.  

 

http://fastestlaps.com/models/renault-zoe

 

You would not tow in the Zoe or most current EVs and they would struggle to zip past a moderately quick vehicle on twisties and that is the price for using current EVs but if we get a similar overtaking feature like some ICE cars have, ie extra boost for overtaking, it should not be a problem for that scenario.          

 

 

 

Edited 27 March, 20179 yr by lol-lol

Ken's two posts actually fully answer the question, with a bit of help from TLV on the gearbox aspect.

I thought that almost all EVs have the power limited to increase the range. (the Tesla's ludicrious setting being the exception)

I think the torque explanation says it all really. I had another look at the P85D dyno and the torque curve is basically one tall peak that immediately drops after it maxes out - which makes sense since power maxes midway and stays there till the end. On the contrary, ICE engines get a steady torque plateau from as low as 2.5K all the way to 5-5.5K and that's were the difference is made. Initially I thought the lack of a gearbox is to blame as well but then I remembered that an ICE dyno is also done in a single gear so I am not sure how much effect that has?

 

In any case, the difference in real world performance is quite significant. Going by non standstill acceleration times it seems that x bhp in a EV equals to (roughly) 0.6x bhp in a Petrol engine so probably that performance reference (of the bhp) we used to have until now to quickly get an idea of how fast a car really is on the road is no longer valid when EV are brought into the discussion.

Hhmm.... 

It isnt that an ev's bhp is about 60% of an ice car, its that the delivery of the power is different.

Just like its different between a diesel and a (non turbo) petrol.

Or a 400bhp car vs a 400bhp lorry. The power is the same but it gets to the road in a totally different way.

So what needs to change isnt our measurement, just how the measurement is presented.

0-60 and 1/4 mile times are purely arbitrary anyway, with driver ability being as big a factor as the power output of the vehicle. Imo...

13 hours ago, mac11irl said:

Hhmm.... 

It isnt that an ev's bhp is about 60% of an ice car, its that the delivery of the power is different.

Just like its different between a diesel and a (non turbo) petrol.

Or a 400bhp car vs a 400bhp lorry. The power is the same but it gets to the road in a totally different way.

So what needs to change isnt our measurement, just how the measurement is presented.

0-60 and 1/4 mile times are purely arbitrary anyway, with driver ability being as big a factor as the power output of the vehicle. Imo...

 

 

Diesel vs Petrol is a very good equivalent that I also thought of, but with EV vs ICE the gap is much bigger in terms of acceleration/performance. Surely x bhp is always x bhp but what I mean is that - it seems that - the way this power is made significantly affects the final performance, so much that in the end it renders the horsepower unit a bit useless as a performance indicator all together.

 

Petrolheads and fact-freaks aside, imagine the typical family estate driver switching to a (say) 350bhp EV and finding out it is clearly weaker in overtaking/real-world acceleration than his old petrol-powered 230bhp Octavia vRS... I think this inherent EV weakness has been hidden so far that everything we have to talk about is 600-700bhp Teslas because 400bhp still feels quite fast for most people but as the electric car market share grows we will definitely see more daily, less powerful, cheaper cars in the 200-400bhp region and then it is going to be quite obvious.