I'm going to get/have my car washed at the dealer today.
They're washing/cleaning my car at the dealership today.
ーI'm going to get/have my car washed at the dealer today.
「今日はディーラーで車を洗ってもらいます」
to get/have my car washed で「車を洗ってもらう」と言えます。
ーThey're washing/cleaning my car at the dealership today.
「今日ディーラで車を洗ってもらう」
they(ディーラーの人)を主語にしてこのように言うこともできます。
ご参考まで!