I found only one site that offered a rate of 199 pounds for 4 adults/1 child. Please help with any other contacts. thanks.

Hi Kitny,
Is there any particular reason why you need to use a car?
National express coach service can get you from Victoria bus station to Bristol in 2.5 hours for around £100 return for the 5 of you. Even cheaper if you are able to book some special tickets. Check their website it can be booked from there.

http://www.nationalexpress.com/

Another option is train, paddington have routes to Bristol Parkway many times a day.

Muck

Since the journey is nearly 140 miles, less than £40 per person for a car/driver doesn't seem that out of whack to me. You certainly might find cheaper, but I can't give you a contact.

I'd personally probably take the train, but the coach service Mucky mentions is a cheaper and almost as easy alternative.

OR - you could rent a car yourselves. A one day rental for an estate (station wagon) would run about £50 or less - pick up in London and drop at Bristol airport.

Have you tried londontown.com? They have car and van services to offer.

We need to catch a flight out of Bristol-US at 11:10am and we're staying in London for a night or two. We're travelling with family (4 adults + 1 child) so car service makes more sense than Hotel-taxi-train or bus-taxi-airport. I just need referrals to car services to find alternate rates. But if 199 is reasonable, then we'll have no choice.

Kitny - You're not thinking of travelling London-Bristol on the morning of your flight, are you?

Assuming you have to check in at least 2 hours before, you would need to leave London extremely early.
And driving around Bristol during the morning rush hour is a big no-no ...

It would be best to spend your last night in Bath or Bristol - and take the airport shuttle bus in the morning.

Steve

Oh, my goodness - w/ the new info, steve_james is right. I'd NEVER try to drive from central London to Bristol for a morning flight.

Too much could go wrong - a tie up on the M4 and you'd be stuck. Plus you'd have to leave your hotel by 5:30 a.m. at the latest, so up by about 4 a.m.

If you haven't seen Bath before - I'd take the train or coach to Bath the day before, stay the night there and arrange a MUCH cheaper car service from Bath to Bristol airport -- and at a reasonable morining hour.

If you don't want to see Bath , there is enough in Bristol to fill an interesting day so you could take the train to Bristol and get a hotel near the airport. Then spend the day touring bristol by public transport.

my 3rd choice would be to hang around London that last day and then in the early evening, take the train/coach/ or car service to Bristol and stay the night near the airport.