He took him for a ride. This is a phrase used to indicate cheating.
But I want to say to my child that I will take her for a ride in my car. How should I say this?
Can I say - "Let me take you for a ride in the car"?
Can I also say - "Let me take you for a ride"?
In English, it's common for simple phrase to have more than one meaning. Usually, people can figure out which meaning applies by the context of your remarks.
For example, as you point out, the sentence, "I want to take you for a ride," could mean a few different things, depending on the situation. When a parent says it to a child, it could mean:
Often, the intended meaning is figured out easily enough by surrounding context:
While it's true that the phrase could mean:
that seems highly unlikely. For one thing, when you want to "take someone for a ride" in that sense, you don't usually start by announcing your intentions.
A lot of idiomatic expressions are figurative, yet they have literal meanings as well. We can tell someone to "go jump in a lake" even when there is no water nearby. You can "have a blast" at work, and that usually means that you're having a good time, although in rare instances it might mean there was an explosion. Usually the intended meaning is pretty obvious, and, in cases where it isn't, any ambiguity can usually be cleared up with a simple follow-up question:
I want to take you for a ride.
Do you mean in the truck, or on our bikes?
"Take somebody for a ride" still has got a meaning "to have fun riding" in a car. Nobody will think you mean "to cheat or even to kill" your child in this context. I think "let me" is too formal here. You'd better say, "Shall we go for a ride in my car?"
People often use the phrase "let me" when they are offering to do something for someone, for example, let me show you (The Free Dictionary).
In light of this definition, I think the OP's sentence as follows is grammatically correct:
Let me take you for a ride in my car.
As for the other sentence "Let me take you for a ride", you can also use it without mentioning "in the/my car", if your child already knows that the ride means the ride in your car. I know a ride may be on a bike, in a car, truck, train, or helicopter, but, more often than not, it means a ride in a car. According to Cambridge Dictionary, a ride also means a free journey in a car to a place where you want to go. Notwithstanding this explanation, I think it's better to say "a ride in a car" to make a clear sentence.
In the UK, we say "Can I give you a lift?". I'm not sure if this is common outside of the US.
