Auris Diesel now petrol?
Discussion
Couldn't help noticing recently that a car mag was testing the new toyota auris hybrid petrol. They said that it was replacing the auris 2.0 tdi and that was Toyota's direction for the future. This really surprised me, because I'm still nit convinced of how a petrol hybrid is much, if any, more efficient than a smallish diesel. Then it's probably more complex on top of that. Don't get it - how do they figure? What's so bad about diesel that a petrol and loads of batteries is better? Why not a diesel and loads of batteries?
Pentoman said:
This really surprised me, because I'm still nit convinced of how a petrol hybrid is much, if any, more efficient than a smallish diesel. Why not a diesel and loads of batteries?
Diesels with their emission controls aren't suitable for running for short amounts of time - with EGR and DPF they'll clog up in no time. A small, simple petrol engine isn't so problematic.Diesel engines in Jap cars are generally not up to much unless they are bought in. Reason being, they don't get much development for Jap and USA markets because people simply don't buy diesels there.
On another note, forget CO2 for a second, diesels create vastly more pollution than a hybrid petrol, so although Toyota don't really need to legislate for that in Europe, it's generally a good thing to move away from diesel.
That said, a diesel is a more efficient option for motorway miles than most hybrids, which work better in traffic.
On another note, forget CO2 for a second, diesels create vastly more pollution than a hybrid petrol, so although Toyota don't really need to legislate for that in Europe, it's generally a good thing to move away from diesel.
That said, a diesel is a more efficient option for motorway miles than most hybrids, which work better in traffic.
Lots of reasons a diesel hybrid isn't a brilliant idea, including:
- Cost: Modern Euro 5 or Euro 6 Diesel is a hugely complicated beast, 2000 bar fuel pump, DPF, close coupled cat, injectors etc all add up to a big price hike over a petrol engine. If you then add the hybrid cost on top then it is vastly more expensive.
- Weight: Diesel engines always weigh more than petrols, often quite a lot more and this will get worse with the addition of things like AdBlue tanks etc. for Euro 6
- Torque: Petrol hybrid gets a nice low-rev torque boost with the electric motor, which gives it a nice flat torque curve as the petrol engine generates its twist higher up the rev range. Diesel by contast gets good low rev-torque anyway, so you are doubling up in an area it doesn't need boosting, impacting on drivability.
- Emissions: As already mentioned, Diesel chucks out lots of nasty stuff and modern diesels needs lots of bits to stop that. The cats and DPFs on Diesels don't love town driving, so wouldn't react well to an on off engine as well.
- Globalisation: Toyota or Honda can sell hybrids in every market in the world and reap the scale benefits of using the same drivetrain in all markets. Diesel hybrids would only really sell in Europe as the US and Japanese emissions regs are equal for petrol and Diesel (Euro 5 allows higher NOx for Diesel). Tier II Bin 5 for the US is more strict than Euro 6 for diesel!
- Cost: Modern Euro 5 or Euro 6 Diesel is a hugely complicated beast, 2000 bar fuel pump, DPF, close coupled cat, injectors etc all add up to a big price hike over a petrol engine. If you then add the hybrid cost on top then it is vastly more expensive.
- Weight: Diesel engines always weigh more than petrols, often quite a lot more and this will get worse with the addition of things like AdBlue tanks etc. for Euro 6
- Torque: Petrol hybrid gets a nice low-rev torque boost with the electric motor, which gives it a nice flat torque curve as the petrol engine generates its twist higher up the rev range. Diesel by contast gets good low rev-torque anyway, so you are doubling up in an area it doesn't need boosting, impacting on drivability.
- Emissions: As already mentioned, Diesel chucks out lots of nasty stuff and modern diesels needs lots of bits to stop that. The cats and DPFs on Diesels don't love town driving, so wouldn't react well to an on off engine as well.
- Globalisation: Toyota or Honda can sell hybrids in every market in the world and reap the scale benefits of using the same drivetrain in all markets. Diesel hybrids would only really sell in Europe as the US and Japanese emissions regs are equal for petrol and Diesel (Euro 5 allows higher NOx for Diesel). Tier II Bin 5 for the US is more strict than Euro 6 for diesel!
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