Kevin Standing's vehicle was taken from his home in Patcham, East Sussex, on Saturday morning. It did not have a tracker and there was no CCTV evidence.
He said he had wrongly assumed an officer would visit him, but he was told there were no lines of inquiry.
Sussex Police said they focused on crimes that "cause most harm".
Mr Standing said he received a letter from the force on Tuesday saying the "investigation was closed" and to check the CCTV footage of local garages.
"It basically says to car thieves in Sussex, 'carry on stealing cars because there's very little chance you're going to get caught'," he said.
Ch Insp Bruce Mathews said proportionate inquiries had been completed.
"Our investigations teams focuses its efforts on the crimes which cause the most harm.
"Operating with new demands against a shrinking budget, we can't do everything but that doesn't mean we will be ruling out certain types of crime such as shoplifting or vehicle crime.
"We will continue to do so where there are lines of inquiry."
The force said a marker had been placed on the vehicle to bring it to the attention of Automatic Number Plate Recognition (ANPR) cameras.

Polling booths opened at 07:00 BST in the area's 15 constituencies, with results expected to be declared after midnight.
Votes will be counted after the polls close at 22:00 BST.
For the latest news from all the counts on Merseyside, go to our election live service or check the results on your constituency profile page.

Patel, 36, took 102 wickets in all formats for the Bears in 2016, which included 69 in the County Championship.
The New Zealander took four five-wicket hauls in the Championship, including two in one game against Surrey in July with career-best figures of 10-123.
He also took 22 wickets on the way to helping his side win the One-Day Cup.
The spinner, who has not played for his country since January 2013, has now earned a recall for the remainder of New Zealand's Test tour of India, following an injury to fellow off-spinner Mark Craig.
Patel who also weighed in with 298 Championship runs, has now taken more than 50 wickets in a season in four-day cricket for five straight seasons, but this season's tally of 69 is his best.

Lorna Waddell, 41, of Kelso, previously admitted obtaining nearly Â£4,000 by fraud while working for Provident Financial Management Services Ltd.
She was given unpaid work as an alternative to custody.
Jedburgh Sheriff Court was told she had breached her payback order. Sentence was deferred until 11 July for reports.
Waddell got five clients to sign loan applications, saying she would receive the capital and repay the loan instalments, in Kelso between February 2012 and February 2013.
However, after receiving the cash no payments were made.
She also admitted that while acting as an agent for the same company she embezzled nearly Â£700 at her home between November 2012 and March 2013.
A motorist whose Â£40,000 Jaguar car was stolen from his driveway has said he is "astounded" after police said they would be closing the case.
[NEXT_CONCEPT]
People are voting across Merseyside in the general and local council elections.
[NEXT_CONCEPT]
Warwickshire off-spinner Jeetan Patel has won the Professional Cricketers' Association (PCA) Most Valuable Player award for a second time.
[NEXT_CONCEPT]
A financial agent who took thousands of pounds by fraud has breached her community payback order by failing to carry out 180 hours unpaid work.