I think that if it 'feels sleazy' to you, then you already know the answer for this situation.
The better way would be to be up front if you plan on following through in your scenario.
But why buy only 10 minutes closer if the other shop has THE BIKE? If you would save a LOT of cash, that's one thing but still IMO you should be up front if you are going to take the other bike for a longer test ride with absolutely no intention of buying it there.
I would buy from who has the bike and who treats me the best. If the bike fits and the further dealer has it and has been interested in my business, that is who I would buy from.
Just my two cents worth...