How to change partners bad driving habits

[HertsBiker]

...without causing offence?
She says I nag. Yes I think I do, but as ever, for good reasons.
Such as not tailgating people. She will do this pretty much all the time despite having smashed 4 vehicles in doing so.
She cuts lanes on roundabouts which really annoys me as one day there will be an accident.
She doesn't lock the car when driving so puts herself at risk of a car jacking. The last two auto locked, this one doesn't. I pointed out that the driver she has just cut up on a roundabout may catch up with her in a queue, and be a mentalist.
Sigh.
I wish I didn't nag, but I can't help it. I Want to point out that she also doesn't use mirrors enough when on the bike, but fear this will cause an argument... She changed lane on me, and failed to spot a police car that was following us!!!!
On the plus side, she parks the car better than I do!
If I didn't care I wouldn't say anything.

[HertsBiker]

TooMany2cvs said:

HertsBiker said:

She doesn't lock the car when driving so puts herself at risk of a car jacking.

Seriously?

And you ride a bike, too? Do you padlock yourself to that?

It's easier to get away from people when on a bike, than blocked in traffic. And so far I've had 2 bad experiences while on bikes, way more in the car... Spread over 28 years of driving that is. Seems road Ragers tend to avoid bikers for the most part. And I'm more worried about her getting hurt than about the car.