i find a dealer gives me informatio about the a car how can i chek if he is honest

What are your concerns exactly?

Look at the CarFax. What is the dealer claiming?

You can enter the VIN number of the car into various websites that will provide unbiased info about the car's history. Try CarFax.com and Bumper.com and autocheck.com. I recommend all 3 because not all the returned history info will overlap. CarFax will provide the original window sticker of the car when it was sold. This can verify many of the options that do or do not exist on the vehicle. It can be very enlightening to see how often the oil was changed, repairs, new tires, etc. Also repairs that were unusual and repeated over and over again. You'll also see where the vehicle was registered each year so you have an idea of where it was owned previously. Edmunds.com can give you a good idea of the value of the vehicle. Note: Some of these sites are chargeable but it's cheap if you discover some ugly things about the vehicle. Call it insurance.