[Kanzeon7]

HI there everyone who reads this.

I live at the bottom of a 'dip' I shall call it. Bottom of U-shaped valley, 1 mile up either side.

I'm driving a Mazda cx5 2.2tdi. Which gives me approximately 19mpg for my first mile, then averages around 35mpg if I try to be good. Its much better on the motorway but I rarely go there.

This is ONE of the reasons I'm changing it. I've settled on a Seat Leon Excellence Lux.
I thought I had decided on the 2.0Tdi 150bhp diesel (supposed to be 65mpg combined...)

They also have a 1.5T petrol with 150bhp which has a slightly better 0-60 figure... Maybe because it's a bit lighter? It had never crossed my mind that because of my peculiar style of driving it may be better for me to opt for the petrol?

I don't know how to calculate / figure this out. Whether I'm better opting for diesel or petrol PURELY ON THE FUEL CONSUMPTION ISSUE.

Taking nothing else into account - ie initial costs, performance, residual values. Only MPG when most of what I do is 1 mile up, 5 - 10 on flat, then a mile down hill again.

Most of the saving will probably come from getting rid of the big heavy beast of a cx5 hopefully?

Thanks very much in anticipation.

[alan1302]

Is there anything else wrong about the Mazda? If not the cost of changing it will be more than any potential saving.

If you are only doing low mileage the petrol is probably a better option as modern diesels are not so suited to short runs.

[Kanzeon7]

Hi Alan!

Thanks for the quick response.

No... As I put at the end of the o/p the question is purely about MPG considering how I use a car. Nothing else to be considered.

Thanks again!

[Hometune]

The diesel engine in your Mazda is notoriously poor especially once it gets some mileage on it. One thing to remember with a petrol is that during cold weather your fuel consumption will rise. If you are unsure of MPG for a particular car - ignore the unachievable official figures - use Honest John's site where owners put up their true MPG. https://www.honestjohn.co.uk/real-mpg/

[wagolynn]

Both petrol and diesel engines, are made by the engine management computer, to run inefficiently while the engine is warming up to speed up the warming up process, the length of time this takes will depend on how much work the engine is doing, and of course ambient temperature.