I'm sure the TDV6 and TDV8 are were developed by Ford with input from Peugeot. As originally stated when TATA purchased LR that they would still have access to these engines.
They COULD have sold this for more than the petrol if they wanted to, not sure why they didn't given Audi's pricing policy.
The reason the petrol is worth more is because it's a BMW. BMW arguably make the best 6 cylinder engines in the world and they should be a premium over a diesel 4 cylinder. Some may say it isn't a real BMW unless it has a 6 cylinder under the bonnet.
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