T. Spark said:
Ok lets take the BMW 530D M Sport @ £40,145
This does 0-60 in 6.8 seconds
50-75mph in 5.1 seconds.
Does a average of 42.8mpg (imperial)
And the BMW 530i M Sport @ £39,820
This does 0-60 in 6.5 seconds
50-75mph in 7.0 seconds
Does a average of 36.7mpg (imperial)
Now lets assume that 'performance' is the same. Aka the diesel is remapped for pure 0-60 whilst the petrol is remapped for extra torque in gear, and therefore they are 'matched' across the range. So this isnt anything to do with performance, simply price per mile.
Using the list price, mpg and the UK national average milage of 12,000 miles, a ownership of 4 years and current average fuel prices of 107.9p for petrol and 117.1p for diesel.
BMW 530D costs you = £46,118
BMW 530i costs you = £46,237
Meaning the BMW 530D actually works out cheaper over the 4 years. However this doesnt include re-sale value's of the car after 4 years, which as we all know will be higher on the 530D rather than the petrol varient. So all in all, if performance was 'matched' the BMW 530D would be the 'better' in terms of price for performance. I'd imagine to the tune of around £600 not including insurance costs.
Now looking at the Seat Leon as a 'normal' smallish car over the BMW. If we take the same 2.0 TDi engine thats used for the BTCC and compare with the petrol version should we see similar results? Lets find out!
Seat Leon FR TDi @ £17,955
This does 0-62 in 8.2 seconds
Is within insurance group 12
And does 47.1mpg
Seat Leon FR TSi @ £17,505
Does 0-62 in 7.3 seconds
Is within insurance group 14
And does 35.8mpg
Again, lets say performance is matched. I myself know for a fact that they always 'under-rate' the diesel's 0-62 time!
Using the list price, mpg and the UK national average milage of 12,000 miles, a ownership of 4 years and current average fuel prices off 107.9p for petrol and 117.1p for diesel.
The Leon TDi costs you = £23,380
The Leon TSi costs you = £24,085
So this time we have a even bigger 'gap' between price. Again still in favour of the TDi varient. Including re-sale value, insurance costs being more on the petrol i'd guestimate a figure in excess off £1,000 saving for the TDi owner.
If you increase the milage per year. As there is some debate on what the 'national' average is. Then does the story change? Working out at 20,000 miles a year (alot!)
Well needless to say it becomes even clearer that gap between diesel and petrol on ownership!
So if a 'diesel' was just as quick as a 'petrol' in everyway. Would you spend circa £1,000 for more turbo lag, less usuable power but a tractor?
** Would like to point out I own neither petrol or diesel varients of either car so hold no bais to any/or and these were simply used as two upto date diesel engines vs their petrol counterparts **