Is it early stages of disease or just plain meanness?

When you say no, are you saying he refuses to see a doctor? I think it's helpful for some people to make a list of the symptoms such as lying, agitated, accusatory, denial, delusions, etc., and take it to the doctor with the patient. The patient doesn't have to know about the list. The doctor needs to know what is going on. Go under the pretense of getting a vaccination or check up the insurance co is now requiring. Anything to get him in. While there the doctor can give him a mini mental evaluation. Take it from there.

I don't know many people who exhibit the symptoms you describe who aren't suffering from some form of mental decline. It might be dementia, mental illness, depression, etc. but something is causing them to not think clearly and to use poor judgment. When they reach the level where they are placing themselves and others in danger, then it's at the point where someone has to step in. It's tough, but someone has to, if their safety is at risk.

I would watch very carefully. These signs that you describe can quickly progress to more severe signs, such as wandering, mistaking or not taking medication, physical aggression, misuse of money or becoming a victim of financial abuse.
I wouldn't just write it off as him being mean. It's probably not that simple.

For both his sake and yours, you need to act quickly and get him in for an evaluation. I've found that if someone always tended to be difficult, dementia onset will exacerbate the problems; if he was always mild, and has begun to be difficult, there is likely some kind of decline in process. I went through ten years of this with my own father. If you're not getting support from your siblings, as I didn't, ya gotta resolve to start the process yourself and reach out to local resources for help. Start with his doctor. He or she will know of agencies that can help you. I hope this all works out for you.

It's difficult to say what causes someone to be mean, but I have seen unusually hostile behavior turn out to be caused by dementia. I suppose there could also be other reasons such as infection, medication interactions, etc. I'd investigate to see if a cause could be discovered. That discovery could also help you get more control over the driving. Is the driving safe? I'd definitely safeguard that activity if I had suspicions of any competence.

Get him to a geriatric psychiatrist.

thank you so much to all for your helpful responses - I have a journal and been documenting, and will have to see how I can get him to Dr - (since he cancelled next weeks visit) stubborn ----again I can't thank you enough for your responses and helpful answers --- knowing your not alone is a huge hug :)

Thanks - no he's just impossible, refuses to give up doing anything including driving on major highways etc. says everyone is trying to kill him and take his independence away everything is negative - I think fear is playing a big roll, his behavior has changed for the worse that last 2 months, anger, yells, turns air off, does things just to irritate people - lies etc etc siblings both out of state in denial -they think it's me --- harder maybe because I'm in the same house?