Hertz UK has Fiat Abarth 500 in their Fun Collection fleet

https://www.hertz.com/rentacar/byr/index.jsp?targetPage=vehicleGuideHomeView.jsp

Hertz UK Fun Collection also includes Volkswagen Scirocco and Alfa Romeo Brera.

Example: One day Abarth 500 rental from London Heatrow in June (friday – saturday) 2011. Price starts 97.88 GBP per day including unlimited mileage, airport location fee, CDW, TP, vehicle licensing fee and taxes. You may get better price using AAA, Credit Card and other  CDP discount codes and promotion PC coupons.

During Hertz Spring Offer 15. – 23.4 you can get Abarth 500 with prepaid rate 86.81 GBP per day.

Sixt Germany has added Porsches to their current fleet

Porsche Fleet consists Panamera, 911 Cabrio, Boster. Porsches are available in limited number of branches in cities Munich, Berlin….

Prices start 169 eur Boxsters, 911’s and Panameras  199 eur / day when booking at least 10 days (including 1000km).

Sixt Porsche Rental Prices for 10 days (daily price)