Car rental England

I found the prices last Fall similar to what you're describing. We booked at https://www.leweschaileycarrental.co.uk/ in Lewes which is a short train ride south of Gatwick. It was less than half the price.

I'd recommend you read Day 1 of my Trip Report before you book to make sure you'll be comfortable with them. It's a small independent business and the cars aren't brand new.
https://community.ricksteves.com/travel-forum/trip-reports/trip-report-the-south-of-england

That rental price doesn’t surprise me unfortunately. It’s the size of the car that is really pushing the price up as what you need is considered very large by British standards. You’re not all going to fit in even a Qashqai sized MPV.

Where in SW England?

It’s October 2023.

You are asking about car rental costs for May 2024.

The size of cars in the UK are usually small and 2 door. Yes there larger vehicles. More costly.

With whom do you rent in the US?

In your research did you look to see if Hertz or Enterprise or Alamo have offices at LHR.

I know I’ve rented via Hertz at LHR. You must board a shuttle bus to take you out to the ring road to where you obtain your vehicle..

With 5 people with luggage you’ll be lucky to find a vehicle that will be large enough.

Maybe a VW Shuttle van.

When you say party of five with luggage what precisely do you mean? Does luggage mean a full size suitcase per person or is it all carry-on?

If it's five separate suitcases then you can forget a car, you won't find one that can accommodate all that luggage. The exception might be a large estate car but I would want to book via a company that guarantees the model. Few companies offer this and those that do generally tend to offer a guarantee only on the very high end models they rent.

Even a minivan might be inadequate as they are geared towards maximum number of passengers rather than storage.

The prices are ridiculous, and have been for at least two years. Try AutoEurope, and keep looking every day. I found an amazing deal on a German 3 week rental of a Ford Galaxy van: under $400 for a manual. For 3 weeks.

You will need a minivan to fit group. An estate car if you want to squish everyone in and everyone does carryon only. Might have to put your daybags on your laps. We are a family of 4 and have rented SUVs. We barely fit with 4 carryons. Estate cars provide much more cargo space.

You will likely need an automatic. Even if you know how to use a manual transmission, in England you are driving on the left and have to use your left hand to shift. An automatic is going to cost more, but it is worth it. Try Autoeurope but n the end, pay whatever the price is to get what you need without the stress.

Appreciate everyone’s wise counsel!