How to clear mpg data and chart

[GasSavers_Graeme]

Seems like I need a bunch of hand holding. I changed cars and updated the car specs, but I haven't figured out how to clear the mpg data and related chart.

Help appreciated.

[JanGeo]

You probably should have created a new garage entry for the new car and retired the old one with all the gas log entries.

[GasSavers_Graeme]

Well, I've tried retiring what's currently there and nothing happens. I go to garage, click on edit, go to bottom and click retire vehicle and the screen goes blank. Any subsequent action reinstates what I'd attempted to retire. Usually I'm not this dense. I'm sure it's just me, but I find some of the site manipulation to be less than clear.

[Lug_Nut]

Re-animated this thread, with a slightly different question:
I'm 'catching up', entering past fueling data to a recent garage entry. The table shows the data in an order based on the calendar date.
Unfortunately the graph chart shows the data in the order in which it was entered. Normally not a problem, but I jumped ahead after entering the first year and began inputting data from the present back in order to see my 90 day history.
The data table is listed by date, but the chart doesn't "fill in". It just adds the next data in the order I typed it in, not in calendar chronological sequence.
I tried to delete the current year's data (for my 90 day average) to remove this sequential error, but am unable to do so.
Any advice on how to remove the non-sequential data from year 2008 so that I can proceed with entering from the 2001 year?

[Lug_Nut]

I think that if I just go back into the 2008 entries I put in, and edit them to change the dates and data to continue from where I left off with the 2001 data, that it will be OK.
I'll try it anyway.
<edit> That worked. I just edited the table entries with the 2001 data in the same reverse calendar order I first entered the 2008 data. The table re-sequenced by the new calandar date and the chart data points reflected the edited data. Now the calendar sequence in the table matches the chart sequence. I'm back on track, but I'll just have to wait until I get the intervening years' data entered to see the most recent 90 days.<end>